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1
+ [
2
+ {
3
+ "task_id": "J2_structural_shortcuts_000476",
4
+ "task_type": "J2_error_detection",
5
+ "category": "structural_shortcuts",
6
+ "problem": "What is 9999 * 5091?",
7
+ "correct_answer": "50904909",
8
+ "ns_solution_with_error": "Using Use (10000-1)*m = 10000*m - 1*m.\nApproximation gives: 50904910",
9
+ "error_type": "arithmetic_slip",
10
+ "error_description": "Arithmetic slip in the shortcut step",
11
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 9999 * 5091?\n\nSolution: Using Use (10000-1)*m = 10000*m - 1*m.\nApproximation gives: 50904910"
12
+ },
13
+ {
14
+ "task_id": "J2_landmark_comparison_000673",
15
+ "task_type": "J2_error_detection",
16
+ "category": "landmark_comparison",
17
+ "problem": "Is 26% of 16520 greater than 4299?",
18
+ "correct_answer": "No",
19
+ "ns_solution_with_error": "Using Use 25% as landmark: 25% of 16520 = 4130.\nApproximation gives: 2147",
20
+ "error_type": "wrong_operand",
21
+ "error_description": "Applied shortcut to wrong operand",
22
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Is 26% of 16520 greater than 4299?\n\nSolution: Using Use 25% as landmark: 25% of 16520 = 4130.\nApproximation gives: 2147"
23
+ },
24
+ {
25
+ "task_id": "J2_equation_reasoning_000722",
26
+ "task_type": "J2_error_detection",
27
+ "category": "equation_reasoning",
28
+ "problem": "What value fills the blank? 2196 × (3976 + 6567) = 2196 × ___ + 2196 × 6567",
29
+ "correct_answer": "3976",
30
+ "ns_solution_with_error": "Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 4174",
31
+ "error_type": "wrong_rounding",
32
+ "error_description": "Rounded in the wrong direction",
33
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What value fills the blank? 2196 × (3976 + 6567) = 2196 × ___ + 2196 × 6567\n\nSolution: Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 4174"
34
+ },
35
+ {
36
+ "task_id": "J2_structural_shortcuts_000466",
37
+ "task_type": "J2_error_detection",
38
+ "category": "structural_shortcuts",
39
+ "problem": "What is 10001 * 9495?",
40
+ "correct_answer": "94959495",
41
+ "ns_solution_with_error": "Using Use (10000+1)*m = 10000*m + 1*m.\nApproximation gives: 99707469",
42
+ "error_type": "wrong_rounding",
43
+ "error_description": "Rounded in the wrong direction",
44
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 10001 * 9495?\n\nSolution: Using Use (10000+1)*m = 10000*m + 1*m.\nApproximation gives: 99707469"
45
+ },
46
+ {
47
+ "task_id": "J2_relative_distance_000510",
48
+ "task_type": "J2_error_detection",
49
+ "category": "relative_distance",
50
+ "problem": "Which is larger: 4794/9750 or 4219/8289?",
51
+ "correct_answer": "4219/8289",
52
+ "ns_solution_with_error": "Using One is below 1/2, the other above; no computation needed.\nApproximation gives: 0",
53
+ "error_type": "wrong_rounding",
54
+ "error_description": "Rounded in the wrong direction",
55
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which is larger: 4794/9750 or 4219/8289?\n\nSolution: Using One is below 1/2, the other above; no computation needed.\nApproximation gives: 0"
56
+ },
57
+ {
58
+ "task_id": "J2_compatible_numbers_000630",
59
+ "task_type": "J2_error_detection",
60
+ "category": "compatible_numbers",
61
+ "problem": "Estimate 5090 × 1947.",
62
+ "correct_answer": "9910230",
63
+ "ns_solution_with_error": "Using Round to 5000×2000 for easy mental computation.\nApproximation gives: 9910228",
64
+ "error_type": "arithmetic_slip",
65
+ "error_description": "Arithmetic slip in the shortcut step",
66
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Estimate 5090 × 1947.\n\nSolution: Using Round to 5000×2000 for easy mental computation.\nApproximation gives: 9910228"
67
+ },
68
+ {
69
+ "task_id": "J2_equation_reasoning_000747",
70
+ "task_type": "J2_error_detection",
71
+ "category": "equation_reasoning",
72
+ "problem": "What value fills the blank? 5045 × (9819 + 3109) = 5045 × ___ + 5045 × 3109",
73
+ "correct_answer": "9819",
74
+ "ns_solution_with_error": "Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 19638",
75
+ "error_type": "wrong_operand",
76
+ "error_description": "Applied shortcut to wrong operand",
77
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What value fills the blank? 5045 × (9819 + 3109) = 5045 × ___ + 5045 × 3109\n\nSolution: Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 19638"
78
+ },
79
+ {
80
+ "task_id": "J2_cancellation_identity_000563",
81
+ "task_type": "J2_error_detection",
82
+ "category": "cancellation_identity",
83
+ "problem": "Evaluate: 6144 + 3597 - 3599",
84
+ "correct_answer": "6142",
85
+ "ns_solution_with_error": "Using Near-cancellation: 3597 - 3599 = -2, so answer ≈ 6144 + -2.\nApproximation gives: 6449",
86
+ "error_type": "wrong_rounding",
87
+ "error_description": "Rounded in the wrong direction",
88
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Evaluate: 6144 + 3597 - 3599\n\nSolution: Using Near-cancellation: 3597 - 3599 = -2, so answer ≈ 6144 + -2.\nApproximation gives: 6449"
89
+ },
90
+ {
91
+ "task_id": "J2_relative_distance_000549",
92
+ "task_type": "J2_error_detection",
93
+ "category": "relative_distance",
94
+ "problem": "Which is larger: 1237/2527 or 1278/2528?",
95
+ "correct_answer": "1278/2528",
96
+ "ns_solution_with_error": "Using One is below 1/2, the other above; no computation needed.\nApproximation gives: 1",
97
+ "error_type": "wrong_rounding",
98
+ "error_description": "Rounded in the wrong direction",
99
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which is larger: 1237/2527 or 1278/2528?\n\nSolution: Using One is below 1/2, the other above; no computation needed.\nApproximation gives: 1"
100
+ },
101
+ {
102
+ "task_id": "J2_structural_shortcuts_000473",
103
+ "task_type": "J2_error_detection",
104
+ "category": "structural_shortcuts",
105
+ "problem": "What is 10002 * 8558?",
106
+ "correct_answer": "85597116",
107
+ "ns_solution_with_error": "Using Use (10000+2)*m = 10000*m + 2*m.\nApproximation gives: 171194232",
108
+ "error_type": "wrong_operand",
109
+ "error_description": "Applied shortcut to wrong operand",
110
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 10002 * 8558?\n\nSolution: Using Use (10000+2)*m = 10000*m + 2*m.\nApproximation gives: 171194232"
111
+ },
112
+ {
113
+ "task_id": "J2_magnitude_estimation_000432",
114
+ "task_type": "J2_error_detection",
115
+ "category": "magnitude_estimation",
116
+ "problem": "Which of the following is the best estimate for 10100 * 10200?",
117
+ "correct_answer": "103020000",
118
+ "ns_solution_with_error": "Using Round both to 10000 and multiply.\nApproximation gives: 108171000",
119
+ "error_type": "wrong_rounding",
120
+ "error_description": "Rounded in the wrong direction",
121
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which of the following is the best estimate for 10100 * 10200?\n\nSolution: Using Round both to 10000 and multiply.\nApproximation gives: 108171000"
122
+ },
123
+ {
124
+ "task_id": "J2_option_elimination_000777",
125
+ "task_type": "J2_error_detection",
126
+ "category": "option_elimination",
127
+ "problem": "What is 7521 × 4423?",
128
+ "correct_answer": "33265383",
129
+ "ns_solution_with_error": "Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 33265380",
130
+ "error_type": "arithmetic_slip",
131
+ "error_description": "Arithmetic slip in the shortcut step",
132
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 7521 × 4423?\n\nSolution: Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 33265380"
133
+ },
134
+ {
135
+ "task_id": "J2_landmark_comparison_000652",
136
+ "task_type": "J2_error_detection",
137
+ "category": "landmark_comparison",
138
+ "problem": "Is 9% of 48380 greater than 22179?",
139
+ "correct_answer": "No",
140
+ "ns_solution_with_error": "Using Use 10% as landmark: 10% of 48380 = 4838.\nApproximation gives: 4357",
141
+ "error_type": "arithmetic_slip",
142
+ "error_description": "Arithmetic slip in the shortcut step",
143
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Is 9% of 48380 greater than 22179?\n\nSolution: Using Use 10% as landmark: 10% of 48380 = 4838.\nApproximation gives: 4357"
144
+ },
145
+ {
146
+ "task_id": "J2_magnitude_estimation_000406",
147
+ "task_type": "J2_error_detection",
148
+ "category": "magnitude_estimation",
149
+ "problem": "Which of the following is the best estimate for 9900 * 9800?",
150
+ "correct_answer": "97020000",
151
+ "ns_solution_with_error": "Using Round both to 10000 and multiply.\nApproximation gives: 97020001",
152
+ "error_type": "arithmetic_slip",
153
+ "error_description": "Arithmetic slip in the shortcut step",
154
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which of the following is the best estimate for 9900 * 9800?\n\nSolution: Using Round both to 10000 and multiply.\nApproximation gives: 97020001"
155
+ },
156
+ {
157
+ "task_id": "J2_equation_reasoning_000728",
158
+ "task_type": "J2_error_detection",
159
+ "category": "equation_reasoning",
160
+ "problem": "What value fills the blank? 6981 × 2792 × 3660 = ___ × 3660 × 6981",
161
+ "correct_answer": "2792",
162
+ "ns_solution_with_error": "Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 2992",
163
+ "error_type": "transcription_error",
164
+ "error_description": "Transcription error in final answer",
165
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What value fills the blank? 6981 × 2792 × 3660 = ___ × 3660 × 6981\n\nSolution: Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 2992"
166
+ },
167
+ {
168
+ "task_id": "J2_compatible_numbers_000618",
169
+ "task_type": "J2_error_detection",
170
+ "category": "compatible_numbers",
171
+ "problem": "Estimate 2540 × 3676.",
172
+ "correct_answer": "9337040",
173
+ "ns_solution_with_error": "Using Round to 2500×4000 for easy mental computation.\nApproximation gives: 9347040",
174
+ "error_type": "transcription_error",
175
+ "error_description": "Transcription error in final answer",
176
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Estimate 2540 × 3676.\n\nSolution: Using Round to 2500×4000 for easy mental computation.\nApproximation gives: 9347040"
177
+ },
178
+ {
179
+ "task_id": "J2_magnitude_estimation_000439",
180
+ "task_type": "J2_error_detection",
181
+ "category": "magnitude_estimation",
182
+ "problem": "Which of the following is the best estimate for 10200 * 10200?",
183
+ "correct_answer": "104040000",
184
+ "ns_solution_with_error": "Using Round both to 10000 and multiply.\nApproximation gives: 208080000",
185
+ "error_type": "wrong_operand",
186
+ "error_description": "Applied shortcut to wrong operand",
187
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which of the following is the best estimate for 10200 * 10200?\n\nSolution: Using Round both to 10000 and multiply.\nApproximation gives: 208080000"
188
+ },
189
+ {
190
+ "task_id": "J2_compatible_numbers_000651",
191
+ "task_type": "J2_error_detection",
192
+ "category": "compatible_numbers",
193
+ "problem": "Estimate 2548 × 3929.",
194
+ "correct_answer": "10011092",
195
+ "ns_solution_with_error": "Using Round to 2500×4000 for easy mental computation.\nApproximation gives: 10511646",
196
+ "error_type": "wrong_rounding",
197
+ "error_description": "Rounded in the wrong direction",
198
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Estimate 2548 × 3929.\n\nSolution: Using Round to 2500×4000 for easy mental computation.\nApproximation gives: 10511646"
199
+ },
200
+ {
201
+ "task_id": "J2_option_elimination_000767",
202
+ "task_type": "J2_error_detection",
203
+ "category": "option_elimination",
204
+ "problem": "What is 6918 × 8652?",
205
+ "correct_answer": "59854536",
206
+ "ns_solution_with_error": "Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 56861810",
207
+ "error_type": "wrong_rounding",
208
+ "error_description": "Rounded in the wrong direction",
209
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 6918 × 8652?\n\nSolution: Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 56861810"
210
+ },
211
+ {
212
+ "task_id": "J2_option_elimination_000765",
213
+ "task_type": "J2_error_detection",
214
+ "category": "option_elimination",
215
+ "problem": "What is 1104 × 5487?",
216
+ "correct_answer": "6057648",
217
+ "ns_solution_with_error": "Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 12115296",
218
+ "error_type": "wrong_operand",
219
+ "error_description": "Applied shortcut to wrong operand",
220
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 1104 × 5487?\n\nSolution: Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 12115296"
221
+ },
222
+ {
223
+ "task_id": "J2_relative_distance_000509",
224
+ "task_type": "J2_error_detection",
225
+ "category": "relative_distance",
226
+ "problem": "Which is larger: 2166/4399 or 1489/2922?",
227
+ "correct_answer": "1489/2922",
228
+ "ns_solution_with_error": "Using One is below 1/2, the other above; no computation needed.\nApproximation gives: 1",
229
+ "error_type": "wrong_operand",
230
+ "error_description": "Applied shortcut to wrong operand",
231
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which is larger: 2166/4399 or 1489/2922?\n\nSolution: Using One is below 1/2, the other above; no computation needed.\nApproximation gives: 1"
232
+ },
233
+ {
234
+ "task_id": "J2_equation_reasoning_000751",
235
+ "task_type": "J2_error_detection",
236
+ "category": "equation_reasoning",
237
+ "problem": "What value fills the blank? 6818 × (3906 + 8051) = 6818 × ___ + 6818 × 8051",
238
+ "correct_answer": "3906",
239
+ "ns_solution_with_error": "Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 4101",
240
+ "error_type": "wrong_rounding",
241
+ "error_description": "Rounded in the wrong direction",
242
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What value fills the blank? 6818 × (3906 + 8051) = 6818 × ___ + 6818 × 8051\n\nSolution: Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 4101"
243
+ },
244
+ {
245
+ "task_id": "J2_cancellation_identity_000557",
246
+ "task_type": "J2_error_detection",
247
+ "category": "cancellation_identity",
248
+ "problem": "Evaluate: 6268 + 4816 - 4818",
249
+ "correct_answer": "6266",
250
+ "ns_solution_with_error": "Using Near-cancellation: 4816 - 4818 = -2, so answer ≈ 6268 + -2.\nApproximation gives: 6579",
251
+ "error_type": "wrong_rounding",
252
+ "error_description": "Rounded in the wrong direction",
253
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Evaluate: 6268 + 4816 - 4818\n\nSolution: Using Near-cancellation: 4816 - 4818 = -2, so answer ≈ 6268 + -2.\nApproximation gives: 6579"
254
+ },
255
+ {
256
+ "task_id": "J2_structural_shortcuts_000457",
257
+ "task_type": "J2_error_detection",
258
+ "category": "structural_shortcuts",
259
+ "problem": "What is 9999 * 2376?",
260
+ "correct_answer": "23757624",
261
+ "ns_solution_with_error": "Using Use (10000-1)*m = 10000*m - 1*m.\nApproximation gives: 22569743",
262
+ "error_type": "wrong_rounding",
263
+ "error_description": "Rounded in the wrong direction",
264
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 9999 * 2376?\n\nSolution: Using Use (10000-1)*m = 10000*m - 1*m.\nApproximation gives: 22569743"
265
+ },
266
+ {
267
+ "task_id": "J2_magnitude_estimation_000411",
268
+ "task_type": "J2_error_detection",
269
+ "category": "magnitude_estimation",
270
+ "problem": "Which of the following is the best estimate for 10100 * 10200?",
271
+ "correct_answer": "103020000",
272
+ "ns_solution_with_error": "Using Round both to 10000 and multiply.\nApproximation gives: 103020002",
273
+ "error_type": "arithmetic_slip",
274
+ "error_description": "Arithmetic slip in the shortcut step",
275
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which of the following is the best estimate for 10100 * 10200?\n\nSolution: Using Round both to 10000 and multiply.\nApproximation gives: 103020002"
276
+ },
277
+ {
278
+ "task_id": "J2_structural_shortcuts_000463",
279
+ "task_type": "J2_error_detection",
280
+ "category": "structural_shortcuts",
281
+ "problem": "What is 10002 * 7974?",
282
+ "correct_answer": "79755948",
283
+ "ns_solution_with_error": "Using Use (10000+2)*m = 10000*m + 2*m.\nApproximation gives: 79755148",
284
+ "error_type": "transcription_error",
285
+ "error_description": "Transcription error in final answer",
286
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 10002 * 7974?\n\nSolution: Using Use (10000+2)*m = 10000*m + 2*m.\nApproximation gives: 79755148"
287
+ },
288
+ {
289
+ "task_id": "J2_magnitude_estimation_000447",
290
+ "task_type": "J2_error_detection",
291
+ "category": "magnitude_estimation",
292
+ "problem": "Which of the following is the best estimate for 9900 * 9900?",
293
+ "correct_answer": "98010000",
294
+ "ns_solution_with_error": "Using Round both to 10000 and multiply.\nApproximation gives: 196020000",
295
+ "error_type": "wrong_operand",
296
+ "error_description": "Applied shortcut to wrong operand",
297
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which of the following is the best estimate for 9900 * 9900?\n\nSolution: Using Round both to 10000 and multiply.\nApproximation gives: 196020000"
298
+ },
299
+ {
300
+ "task_id": "J2_equation_reasoning_000732",
301
+ "task_type": "J2_error_detection",
302
+ "category": "equation_reasoning",
303
+ "problem": "What value fills the blank? 1558 × 4896 × 3652 = ___ × 3652 × 1558",
304
+ "correct_answer": "4896",
305
+ "ns_solution_with_error": "Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 9792",
306
+ "error_type": "wrong_operand",
307
+ "error_description": "Applied shortcut to wrong operand",
308
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What value fills the blank? 1558 × 4896 × 3652 = ___ × 3652 × 1558\n\nSolution: Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 9792"
309
+ },
310
+ {
311
+ "task_id": "J2_option_elimination_000775",
312
+ "task_type": "J2_error_detection",
313
+ "category": "option_elimination",
314
+ "problem": "What is 5559 × 9837?",
315
+ "correct_answer": "54683883",
316
+ "ns_solution_with_error": "Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 57418077",
317
+ "error_type": "wrong_rounding",
318
+ "error_description": "Rounded in the wrong direction",
319
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 5559 × 9837?\n\nSolution: Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 57418077"
320
+ },
321
+ {
322
+ "task_id": "J2_compatible_numbers_000611",
323
+ "task_type": "J2_error_detection",
324
+ "category": "compatible_numbers",
325
+ "problem": "Estimate 1273 × 7425.",
326
+ "correct_answer": "9452025",
327
+ "ns_solution_with_error": "Using Round to 1250×8000 for easy mental computation.\nApproximation gives: 9452023",
328
+ "error_type": "arithmetic_slip",
329
+ "error_description": "Arithmetic slip in the shortcut step",
330
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Estimate 1273 × 7425.\n\nSolution: Using Round to 1250×8000 for easy mental computation.\nApproximation gives: 9452023"
331
+ },
332
+ {
333
+ "task_id": "J2_cancellation_identity_000579",
334
+ "task_type": "J2_error_detection",
335
+ "category": "cancellation_identity",
336
+ "problem": "Evaluate: 1817 + 5124 - 5125",
337
+ "correct_answer": "1816",
338
+ "ns_solution_with_error": "Using Near-cancellation: 5124 - 5125 = -1, so answer ≈ 1817 + -1.\nApproximation gives: 908",
339
+ "error_type": "wrong_operand",
340
+ "error_description": "Applied shortcut to wrong operand",
341
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Evaluate: 1817 + 5124 - 5125\n\nSolution: Using Near-cancellation: 5124 - 5125 = -1, so answer ≈ 1817 + -1.\nApproximation gives: 908"
342
+ },
343
+ {
344
+ "task_id": "J2_structural_shortcuts_000496",
345
+ "task_type": "J2_error_detection",
346
+ "category": "structural_shortcuts",
347
+ "problem": "What is 9998 * 3721?",
348
+ "correct_answer": "37202558",
349
+ "ns_solution_with_error": "Using Use (10000-2)*m = 10000*m - 2*m.\nApproximation gives: 18601279",
350
+ "error_type": "wrong_operand",
351
+ "error_description": "Applied shortcut to wrong operand",
352
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 9998 * 3721?\n\nSolution: Using Use (10000-2)*m = 10000*m - 2*m.\nApproximation gives: 18601279"
353
+ },
354
+ {
355
+ "task_id": "J2_landmark_comparison_000686",
356
+ "task_type": "J2_error_detection",
357
+ "category": "landmark_comparison",
358
+ "problem": "Is 10% of 85760 greater than 36782?",
359
+ "correct_answer": "No",
360
+ "ns_solution_with_error": "Using Use 10% as landmark: 10% of 85760 = 8576.\nApproximation gives: 8148",
361
+ "error_type": "wrong_rounding",
362
+ "error_description": "Rounded in the wrong direction",
363
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Is 10% of 85760 greater than 36782?\n\nSolution: Using Use 10% as landmark: 10% of 85760 = 8576.\nApproximation gives: 8148"
364
+ },
365
+ {
366
+ "task_id": "J2_landmark_comparison_000661",
367
+ "task_type": "J2_error_detection",
368
+ "category": "landmark_comparison",
369
+ "problem": "Is 27% of 97500 greater than 21848?",
370
+ "correct_answer": "Yes",
371
+ "ns_solution_with_error": "Using Use 25% as landmark: 25% of 97500 = 24375.\nApproximation gives: 25009",
372
+ "error_type": "wrong_rounding",
373
+ "error_description": "Rounded in the wrong direction",
374
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Is 27% of 97500 greater than 21848?\n\nSolution: Using Use 25% as landmark: 25% of 97500 = 24375.\nApproximation gives: 25009"
375
+ },
376
+ {
377
+ "task_id": "J2_relative_distance_000513",
378
+ "task_type": "J2_error_detection",
379
+ "category": "relative_distance",
380
+ "problem": "Which is larger: 884/1785 or 1924/3797?",
381
+ "correct_answer": "1924/3797",
382
+ "ns_solution_with_error": "Using One is below 1/2, the other above; no computation needed.\nApproximation gives: 5",
383
+ "error_type": "arithmetic_slip",
384
+ "error_description": "Arithmetic slip in the shortcut step",
385
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which is larger: 884/1785 or 1924/3797?\n\nSolution: Using One is below 1/2, the other above; no computation needed.\nApproximation gives: 5"
386
+ },
387
+ {
388
+ "task_id": "J2_compatible_numbers_000640",
389
+ "task_type": "J2_error_detection",
390
+ "category": "compatible_numbers",
391
+ "problem": "Estimate 1228 × 7243.",
392
+ "correct_answer": "8894404",
393
+ "ns_solution_with_error": "Using Round to 1250×8000 for easy mental computation.\nApproximation gives: 4447202",
394
+ "error_type": "wrong_operand",
395
+ "error_description": "Applied shortcut to wrong operand",
396
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Estimate 1228 × 7243.\n\nSolution: Using Round to 1250×8000 for easy mental computation.\nApproximation gives: 4447202"
397
+ },
398
+ {
399
+ "task_id": "J2_landmark_comparison_000691",
400
+ "task_type": "J2_error_detection",
401
+ "category": "landmark_comparison",
402
+ "problem": "Is 25% of 89710 greater than 36335?",
403
+ "correct_answer": "No",
404
+ "ns_solution_with_error": "Using Use 25% as landmark: 25% of 89710 = 22427.\nApproximation gives: 23548",
405
+ "error_type": "wrong_rounding",
406
+ "error_description": "Rounded in the wrong direction",
407
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Is 25% of 89710 greater than 36335?\n\nSolution: Using Use 25% as landmark: 25% of 89710 = 22427.\nApproximation gives: 23548"
408
+ },
409
+ {
410
+ "task_id": "J2_equation_reasoning_000724",
411
+ "task_type": "J2_error_detection",
412
+ "category": "equation_reasoning",
413
+ "problem": "What value fills the blank? 7951 × 5441 × 4817 = ___ × 4817 × 7951",
414
+ "correct_answer": "5441",
415
+ "ns_solution_with_error": "Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 5438",
416
+ "error_type": "arithmetic_slip",
417
+ "error_description": "Arithmetic slip in the shortcut step",
418
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What value fills the blank? 7951 × 5441 × 4817 = ___ × 4817 × 7951\n\nSolution: Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 5438"
419
+ },
420
+ {
421
+ "task_id": "J2_cancellation_identity_000568",
422
+ "task_type": "J2_error_detection",
423
+ "category": "cancellation_identity",
424
+ "problem": "Evaluate: 9227 + 8064 - 8063",
425
+ "correct_answer": "9228",
426
+ "ns_solution_with_error": "Using Near-cancellation: 8064 - 8063 = 1, so answer ≈ 9227 + 1.\nApproximation gives: 9225",
427
+ "error_type": "arithmetic_slip",
428
+ "error_description": "Arithmetic slip in the shortcut step",
429
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Evaluate: 9227 + 8064 - 8063\n\nSolution: Using Near-cancellation: 8064 - 8063 = 1, so answer ≈ 9227 + 1.\nApproximation gives: 9225"
430
+ },
431
+ {
432
+ "task_id": "J2_relative_distance_000519",
433
+ "task_type": "J2_error_detection",
434
+ "category": "relative_distance",
435
+ "problem": "Which is larger: 1536/3087 or 3213/6322?",
436
+ "correct_answer": "3213/6322",
437
+ "ns_solution_with_error": "Using One is below 1/2, the other above; no computation needed.\nApproximation gives: 0",
438
+ "error_type": "transcription_error",
439
+ "error_description": "Transcription error in final answer",
440
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which is larger: 1536/3087 or 3213/6322?\n\nSolution: Using One is below 1/2, the other above; no computation needed.\nApproximation gives: 0"
441
+ },
442
+ {
443
+ "task_id": "J2_cancellation_identity_000565",
444
+ "task_type": "J2_error_detection",
445
+ "category": "cancellation_identity",
446
+ "problem": "Evaluate: 2712 + 6582 - 6583",
447
+ "correct_answer": "2711",
448
+ "ns_solution_with_error": "Using Near-cancellation: 6582 - 6583 = -1, so answer ≈ 2712 + -1.\nApproximation gives: 4711",
449
+ "error_type": "transcription_error",
450
+ "error_description": "Transcription error in final answer",
451
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Evaluate: 2712 + 6582 - 6583\n\nSolution: Using Near-cancellation: 6582 - 6583 = -1, so answer ≈ 2712 + -1.\nApproximation gives: 4711"
452
+ },
453
+ {
454
+ "task_id": "J2_landmark_comparison_000683",
455
+ "task_type": "J2_error_detection",
456
+ "category": "landmark_comparison",
457
+ "problem": "Is 27% of 87480 greater than 24547?",
458
+ "correct_answer": "No",
459
+ "ns_solution_with_error": "Using Use 25% as landmark: 25% of 87480 = 21870.\nApproximation gives: 11809",
460
+ "error_type": "wrong_operand",
461
+ "error_description": "Applied shortcut to wrong operand",
462
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Is 27% of 87480 greater than 24547?\n\nSolution: Using Use 25% as landmark: 25% of 87480 = 21870.\nApproximation gives: 11809"
463
+ },
464
+ {
465
+ "task_id": "J2_relative_distance_000534",
466
+ "task_type": "J2_error_detection",
467
+ "category": "relative_distance",
468
+ "problem": "Which is larger: 4320/8812 or 1806/3591?",
469
+ "correct_answer": "1806/3591",
470
+ "ns_solution_with_error": "Using One is below 1/2, the other above; no computation needed.\nApproximation gives: 1",
471
+ "error_type": "wrong_operand",
472
+ "error_description": "Applied shortcut to wrong operand",
473
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which is larger: 4320/8812 or 1806/3591?\n\nSolution: Using One is below 1/2, the other above; no computation needed.\nApproximation gives: 1"
474
+ },
475
+ {
476
+ "task_id": "J2_magnitude_estimation_000409",
477
+ "task_type": "J2_error_detection",
478
+ "category": "magnitude_estimation",
479
+ "problem": "Which of the following is the best estimate for 10200 * 10100?",
480
+ "correct_answer": "103020000",
481
+ "ns_solution_with_error": "Using Round both to 10000 and multiply.\nApproximation gives: 103320000",
482
+ "error_type": "transcription_error",
483
+ "error_description": "Transcription error in final answer",
484
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which of the following is the best estimate for 10200 * 10100?\n\nSolution: Using Round both to 10000 and multiply.\nApproximation gives: 103320000"
485
+ },
486
+ {
487
+ "task_id": "J2_cancellation_identity_000596",
488
+ "task_type": "J2_error_detection",
489
+ "category": "cancellation_identity",
490
+ "problem": "Evaluate: 9205 + 6773 - 6772",
491
+ "correct_answer": "9206",
492
+ "ns_solution_with_error": "Using Near-cancellation: 6773 - 6772 = 1, so answer ≈ 9205 + 1.\nApproximation gives: 9306",
493
+ "error_type": "transcription_error",
494
+ "error_description": "Transcription error in final answer",
495
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Evaluate: 9205 + 6773 - 6772\n\nSolution: Using Near-cancellation: 6773 - 6772 = 1, so answer ≈ 9205 + 1.\nApproximation gives: 9306"
496
+ },
497
+ {
498
+ "task_id": "J2_structural_shortcuts_000470",
499
+ "task_type": "J2_error_detection",
500
+ "category": "structural_shortcuts",
501
+ "problem": "What is 9998 * 7447?",
502
+ "correct_answer": "74455106",
503
+ "ns_solution_with_error": "Using Use (10000-2)*m = 10000*m - 2*m.\nApproximation gives: 148910212",
504
+ "error_type": "wrong_operand",
505
+ "error_description": "Applied shortcut to wrong operand",
506
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 9998 * 7447?\n\nSolution: Using Use (10000-2)*m = 10000*m - 2*m.\nApproximation gives: 148910212"
507
+ },
508
+ {
509
+ "task_id": "J2_structural_shortcuts_000474",
510
+ "task_type": "J2_error_detection",
511
+ "category": "structural_shortcuts",
512
+ "problem": "What is 9999 * 5819?",
513
+ "correct_answer": "58184181",
514
+ "ns_solution_with_error": "Using Use (10000-1)*m = 10000*m - 1*m.\nApproximation gives: 29092090",
515
+ "error_type": "wrong_operand",
516
+ "error_description": "Applied shortcut to wrong operand",
517
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 9999 * 5819?\n\nSolution: Using Use (10000-1)*m = 10000*m - 1*m.\nApproximation gives: 29092090"
518
+ },
519
+ {
520
+ "task_id": "J2_option_elimination_000781",
521
+ "task_type": "J2_error_detection",
522
+ "category": "option_elimination",
523
+ "problem": "What is 1459 × 1977?",
524
+ "correct_answer": "2884443",
525
+ "ns_solution_with_error": "Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 3884443",
526
+ "error_type": "transcription_error",
527
+ "error_description": "Transcription error in final answer",
528
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 1459 × 1977?\n\nSolution: Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 3884443"
529
+ },
530
+ {
531
+ "task_id": "J2_structural_shortcuts_000475",
532
+ "task_type": "J2_error_detection",
533
+ "category": "structural_shortcuts",
534
+ "problem": "What is 9998 * 9721?",
535
+ "correct_answer": "97190558",
536
+ "ns_solution_with_error": "Using Use (10000-2)*m = 10000*m - 2*m.\nApproximation gives: 102050085",
537
+ "error_type": "wrong_rounding",
538
+ "error_description": "Rounded in the wrong direction",
539
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 9998 * 9721?\n\nSolution: Using Use (10000-2)*m = 10000*m - 2*m.\nApproximation gives: 102050085"
540
+ },
541
+ {
542
+ "task_id": "J2_landmark_comparison_000665",
543
+ "task_type": "J2_error_detection",
544
+ "category": "landmark_comparison",
545
+ "problem": "Is 27% of 34690 greater than 11606?",
546
+ "correct_answer": "No",
547
+ "ns_solution_with_error": "Using Use 25% as landmark: 25% of 34690 = 8672.\nApproximation gives: 2366",
548
+ "error_type": "transcription_error",
549
+ "error_description": "Transcription error in final answer",
550
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Is 27% of 34690 greater than 11606?\n\nSolution: Using Use 25% as landmark: 25% of 34690 = 8672.\nApproximation gives: 2366"
551
+ },
552
+ {
553
+ "task_id": "J2_magnitude_estimation_000446",
554
+ "task_type": "J2_error_detection",
555
+ "category": "magnitude_estimation",
556
+ "problem": "Which of the following is the best estimate for 10100 * 9900?",
557
+ "correct_answer": "99990000",
558
+ "ns_solution_with_error": "Using Round both to 10000 and multiply.\nApproximation gives: 99990020",
559
+ "error_type": "transcription_error",
560
+ "error_description": "Transcription error in final answer",
561
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which of the following is the best estimate for 10100 * 9900?\n\nSolution: Using Round both to 10000 and multiply.\nApproximation gives: 99990020"
562
+ },
563
+ {
564
+ "task_id": "J2_landmark_comparison_000679",
565
+ "task_type": "J2_error_detection",
566
+ "category": "landmark_comparison",
567
+ "problem": "Is 48% of 63500 greater than 24915?",
568
+ "correct_answer": "Yes",
569
+ "ns_solution_with_error": "Using Use 50% as landmark: 50% of 63500 = 31750.\nApproximation gives: 30477",
570
+ "error_type": "arithmetic_slip",
571
+ "error_description": "Arithmetic slip in the shortcut step",
572
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Is 48% of 63500 greater than 24915?\n\nSolution: Using Use 50% as landmark: 50% of 63500 = 31750.\nApproximation gives: 30477"
573
+ },
574
+ {
575
+ "task_id": "J2_structural_shortcuts_000499",
576
+ "task_type": "J2_error_detection",
577
+ "category": "structural_shortcuts",
578
+ "problem": "What is 9998 * 1050?",
579
+ "correct_answer": "10497900",
580
+ "ns_solution_with_error": "Using Use (10000-2)*m = 10000*m - 2*m.\nApproximation gives: 10497901",
581
+ "error_type": "arithmetic_slip",
582
+ "error_description": "Arithmetic slip in the shortcut step",
583
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 9998 * 1050?\n\nSolution: Using Use (10000-2)*m = 10000*m - 2*m.\nApproximation gives: 10497901"
584
+ },
585
+ {
586
+ "task_id": "J2_option_elimination_000771",
587
+ "task_type": "J2_error_detection",
588
+ "category": "option_elimination",
589
+ "problem": "What is 5562 × 7803?",
590
+ "correct_answer": "43400286",
591
+ "ns_solution_with_error": "Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 41230272",
592
+ "error_type": "wrong_rounding",
593
+ "error_description": "Rounded in the wrong direction",
594
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 5562 × 7803?\n\nSolution: Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 41230272"
595
+ },
596
+ {
597
+ "task_id": "J2_magnitude_estimation_000419",
598
+ "task_type": "J2_error_detection",
599
+ "category": "magnitude_estimation",
600
+ "problem": "Which of the following is the best estimate for 10100 * 10100?",
601
+ "correct_answer": "102010000",
602
+ "ns_solution_with_error": "Using Round both to 10000 and multiply.\nApproximation gives: 102210000",
603
+ "error_type": "transcription_error",
604
+ "error_description": "Transcription error in final answer",
605
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which of the following is the best estimate for 10100 * 10100?\n\nSolution: Using Round both to 10000 and multiply.\nApproximation gives: 102210000"
606
+ },
607
+ {
608
+ "task_id": "J2_equation_reasoning_000737",
609
+ "task_type": "J2_error_detection",
610
+ "category": "equation_reasoning",
611
+ "problem": "What value fills the blank? 6741 × 2155 × 4707 = ___ × 4707 × 6741",
612
+ "correct_answer": "2155",
613
+ "ns_solution_with_error": "Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 2048",
614
+ "error_type": "wrong_rounding",
615
+ "error_description": "Rounded in the wrong direction",
616
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What value fills the blank? 6741 × 2155 × 4707 = ___ × 4707 × 6741\n\nSolution: Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 2048"
617
+ },
618
+ {
619
+ "task_id": "J2_cancellation_identity_000578",
620
+ "task_type": "J2_error_detection",
621
+ "category": "cancellation_identity",
622
+ "problem": "Evaluate: 5722 + 2063 - 2062",
623
+ "correct_answer": "5723",
624
+ "ns_solution_with_error": "Using Near-cancellation: 2063 - 2062 = 1, so answer ≈ 5722 + 1.\nApproximation gives: 5724",
625
+ "error_type": "arithmetic_slip",
626
+ "error_description": "Arithmetic slip in the shortcut step",
627
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Evaluate: 5722 + 2063 - 2062\n\nSolution: Using Near-cancellation: 2063 - 2062 = 1, so answer ≈ 5722 + 1.\nApproximation gives: 5724"
628
+ },
629
+ {
630
+ "task_id": "J2_equation_reasoning_000736",
631
+ "task_type": "J2_error_detection",
632
+ "category": "equation_reasoning",
633
+ "problem": "What value fills the blank? 3230 × (5915 + 1005) = 3230 × ___ + 3230 × 1005",
634
+ "correct_answer": "5915",
635
+ "ns_solution_with_error": "Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 2957",
636
+ "error_type": "wrong_operand",
637
+ "error_description": "Applied shortcut to wrong operand",
638
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What value fills the blank? 3230 × (5915 + 1005) = 3230 × ___ + 3230 × 1005\n\nSolution: Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 2957"
639
+ },
640
+ {
641
+ "task_id": "J2_structural_shortcuts_000481",
642
+ "task_type": "J2_error_detection",
643
+ "category": "structural_shortcuts",
644
+ "problem": "What is 9998 * 4811?",
645
+ "correct_answer": "48100378",
646
+ "ns_solution_with_error": "Using Use (10000-2)*m = 10000*m - 2*m.\nApproximation gives: 48100398",
647
+ "error_type": "transcription_error",
648
+ "error_description": "Transcription error in final answer",
649
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 9998 * 4811?\n\nSolution: Using Use (10000-2)*m = 10000*m - 2*m.\nApproximation gives: 48100398"
650
+ },
651
+ {
652
+ "task_id": "J2_magnitude_estimation_000433",
653
+ "task_type": "J2_error_detection",
654
+ "category": "magnitude_estimation",
655
+ "problem": "Which of the following is the best estimate for 10200 * 9800?",
656
+ "correct_answer": "99960000",
657
+ "ns_solution_with_error": "Using Round both to 10000 and multiply.\nApproximation gives: 94962000",
658
+ "error_type": "wrong_rounding",
659
+ "error_description": "Rounded in the wrong direction",
660
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which of the following is the best estimate for 10200 * 9800?\n\nSolution: Using Round both to 10000 and multiply.\nApproximation gives: 94962000"
661
+ },
662
+ {
663
+ "task_id": "J2_relative_distance_000547",
664
+ "task_type": "J2_error_detection",
665
+ "category": "relative_distance",
666
+ "problem": "Which is larger: 1518/3038 or 3432/6744?",
667
+ "correct_answer": "3432/6744",
668
+ "ns_solution_with_error": "Using One is below 1/2, the other above; no computation needed.\nApproximation gives: 0",
669
+ "error_type": "transcription_error",
670
+ "error_description": "Transcription error in final answer",
671
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which is larger: 1518/3038 or 3432/6744?\n\nSolution: Using One is below 1/2, the other above; no computation needed.\nApproximation gives: 0"
672
+ },
673
+ {
674
+ "task_id": "J2_cancellation_identity_000567",
675
+ "task_type": "J2_error_detection",
676
+ "category": "cancellation_identity",
677
+ "problem": "Evaluate: 4064 + 5375 - 5377",
678
+ "correct_answer": "4062",
679
+ "ns_solution_with_error": "Using Near-cancellation: 5375 - 5377 = -2, so answer ≈ 4064 + -2.\nApproximation gives: 4262",
680
+ "error_type": "transcription_error",
681
+ "error_description": "Transcription error in final answer",
682
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Evaluate: 4064 + 5375 - 5377\n\nSolution: Using Near-cancellation: 5375 - 5377 = -2, so answer ≈ 4064 + -2.\nApproximation gives: 4262"
683
+ },
684
+ {
685
+ "task_id": "J2_equation_reasoning_000702",
686
+ "task_type": "J2_error_detection",
687
+ "category": "equation_reasoning",
688
+ "problem": "What value fills the blank? 8731 × 2490 × 7066 = ___ × 7066 × 8731",
689
+ "correct_answer": "2490",
690
+ "ns_solution_with_error": "Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 2614",
691
+ "error_type": "wrong_rounding",
692
+ "error_description": "Rounded in the wrong direction",
693
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What value fills the blank? 8731 × 2490 × 7066 = ___ × 7066 × 8731\n\nSolution: Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 2614"
694
+ },
695
+ {
696
+ "task_id": "J2_option_elimination_000801",
697
+ "task_type": "J2_error_detection",
698
+ "category": "option_elimination",
699
+ "problem": "What is 2531 × 7515?",
700
+ "correct_answer": "19020465",
701
+ "ns_solution_with_error": "Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 9510232",
702
+ "error_type": "wrong_operand",
703
+ "error_description": "Applied shortcut to wrong operand",
704
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 2531 × 7515?\n\nSolution: Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 9510232"
705
+ },
706
+ {
707
+ "task_id": "J2_option_elimination_000794",
708
+ "task_type": "J2_error_detection",
709
+ "category": "option_elimination",
710
+ "problem": "What is 2277 × 4068?",
711
+ "correct_answer": "9262836",
712
+ "ns_solution_with_error": "Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 8799695",
713
+ "error_type": "wrong_rounding",
714
+ "error_description": "Rounded in the wrong direction",
715
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 2277 × 4068?\n\nSolution: Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 8799695"
716
+ },
717
+ {
718
+ "task_id": "J2_cancellation_identity_000585",
719
+ "task_type": "J2_error_detection",
720
+ "category": "cancellation_identity",
721
+ "problem": "Evaluate: 4359 + 9463 - 9464",
722
+ "correct_answer": "4358",
723
+ "ns_solution_with_error": "Using Near-cancellation: 9463 - 9464 = -1, so answer ≈ 4359 + -1.\nApproximation gives: 8716",
724
+ "error_type": "wrong_operand",
725
+ "error_description": "Applied shortcut to wrong operand",
726
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Evaluate: 4359 + 9463 - 9464\n\nSolution: Using Near-cancellation: 9463 - 9464 = -1, so answer ≈ 4359 + -1.\nApproximation gives: 8716"
727
+ },
728
+ {
729
+ "task_id": "J2_compatible_numbers_000623",
730
+ "task_type": "J2_error_detection",
731
+ "category": "compatible_numbers",
732
+ "problem": "Estimate 4966 × 1988.",
733
+ "correct_answer": "9872408",
734
+ "ns_solution_with_error": "Using Round to 5000×2000 for easy mental computation.\nApproximation gives: 19744816",
735
+ "error_type": "wrong_operand",
736
+ "error_description": "Applied shortcut to wrong operand",
737
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Estimate 4966 × 1988.\n\nSolution: Using Round to 5000×2000 for easy mental computation.\nApproximation gives: 19744816"
738
+ },
739
+ {
740
+ "task_id": "J2_relative_distance_000520",
741
+ "task_type": "J2_error_detection",
742
+ "category": "relative_distance",
743
+ "problem": "Which is larger: 4625/9376 or 2049/4061?",
744
+ "correct_answer": "2049/4061",
745
+ "ns_solution_with_error": "Using One is below 1/2, the other above; no computation needed.\nApproximation gives: 0",
746
+ "error_type": "wrong_operand",
747
+ "error_description": "Applied shortcut to wrong operand",
748
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which is larger: 4625/9376 or 2049/4061?\n\nSolution: Using One is below 1/2, the other above; no computation needed.\nApproximation gives: 0"
749
+ },
750
+ {
751
+ "task_id": "J2_relative_distance_000501",
752
+ "task_type": "J2_error_detection",
753
+ "category": "relative_distance",
754
+ "problem": "Which is larger: 3746/7556 or 1181/2333?",
755
+ "correct_answer": "1181/2333",
756
+ "ns_solution_with_error": "Using One is below 1/2, the other above; no computation needed.\nApproximation gives: -4",
757
+ "error_type": "arithmetic_slip",
758
+ "error_description": "Arithmetic slip in the shortcut step",
759
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which is larger: 3746/7556 or 1181/2333?\n\nSolution: Using One is below 1/2, the other above; no computation needed.\nApproximation gives: -4"
760
+ },
761
+ {
762
+ "task_id": "J2_compatible_numbers_000638",
763
+ "task_type": "J2_error_detection",
764
+ "category": "compatible_numbers",
765
+ "problem": "Estimate 2548 × 3929.",
766
+ "correct_answer": "10011092",
767
+ "ns_solution_with_error": "Using Round to 2500×4000 for easy mental computation.\nApproximation gives: 10011093",
768
+ "error_type": "transcription_error",
769
+ "error_description": "Transcription error in final answer",
770
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Estimate 2548 × 3929.\n\nSolution: Using Round to 2500×4000 for easy mental computation.\nApproximation gives: 10011093"
771
+ },
772
+ {
773
+ "task_id": "J2_compatible_numbers_000608",
774
+ "task_type": "J2_error_detection",
775
+ "category": "compatible_numbers",
776
+ "problem": "Estimate 5009 × 1968.",
777
+ "correct_answer": "9857712",
778
+ "ns_solution_with_error": "Using Round to 5000×2000 for easy mental computation.\nApproximation gives: 10350597",
779
+ "error_type": "wrong_rounding",
780
+ "error_description": "Rounded in the wrong direction",
781
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Estimate 5009 × 1968.\n\nSolution: Using Round to 5000×2000 for easy mental computation.\nApproximation gives: 10350597"
782
+ },
783
+ {
784
+ "task_id": "J2_landmark_comparison_000659",
785
+ "task_type": "J2_error_detection",
786
+ "category": "landmark_comparison",
787
+ "problem": "Is 10% of 71650 greater than 29517?",
788
+ "correct_answer": "No",
789
+ "ns_solution_with_error": "Using Use 10% as landmark: 10% of 71650 = 7165.\nApproximation gives: 7166",
790
+ "error_type": "transcription_error",
791
+ "error_description": "Transcription error in final answer",
792
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Is 10% of 71650 greater than 29517?\n\nSolution: Using Use 10% as landmark: 10% of 71650 = 7165.\nApproximation gives: 7166"
793
+ },
794
+ {
795
+ "task_id": "J2_structural_shortcuts_000471",
796
+ "task_type": "J2_error_detection",
797
+ "category": "structural_shortcuts",
798
+ "problem": "What is 9998 * 7041?",
799
+ "correct_answer": "70395918",
800
+ "ns_solution_with_error": "Using Use (10000-2)*m = 10000*m - 2*m.\nApproximation gives: 70395915",
801
+ "error_type": "arithmetic_slip",
802
+ "error_description": "Arithmetic slip in the shortcut step",
803
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 9998 * 7041?\n\nSolution: Using Use (10000-2)*m = 10000*m - 2*m.\nApproximation gives: 70395915"
804
+ },
805
+ {
806
+ "task_id": "J2_relative_distance_000523",
807
+ "task_type": "J2_error_detection",
808
+ "category": "relative_distance",
809
+ "problem": "Which is larger: 1473/2971 or 843/1672?",
810
+ "correct_answer": "843/1672",
811
+ "ns_solution_with_error": "Using One is below 1/2, the other above; no computation needed.\nApproximation gives: 0",
812
+ "error_type": "transcription_error",
813
+ "error_description": "Transcription error in final answer",
814
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which is larger: 1473/2971 or 843/1672?\n\nSolution: Using One is below 1/2, the other above; no computation needed.\nApproximation gives: 0"
815
+ },
816
+ {
817
+ "task_id": "J2_magnitude_estimation_000422",
818
+ "task_type": "J2_error_detection",
819
+ "category": "magnitude_estimation",
820
+ "problem": "Which of the following is the best estimate for 9800 * 10200?",
821
+ "correct_answer": "99960000",
822
+ "ns_solution_with_error": "Using Round both to 10000 and multiply.\nApproximation gives: 94962000",
823
+ "error_type": "wrong_rounding",
824
+ "error_description": "Rounded in the wrong direction",
825
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which of the following is the best estimate for 9800 * 10200?\n\nSolution: Using Round both to 10000 and multiply.\nApproximation gives: 94962000"
826
+ },
827
+ {
828
+ "task_id": "J2_cancellation_identity_000591",
829
+ "task_type": "J2_error_detection",
830
+ "category": "cancellation_identity",
831
+ "problem": "Evaluate: 8528 + 3299 - 3298",
832
+ "correct_answer": "8529",
833
+ "ns_solution_with_error": "Using Near-cancellation: 3299 - 3298 = 1, so answer ≈ 8528 + 1.\nApproximation gives: 17058",
834
+ "error_type": "wrong_operand",
835
+ "error_description": "Applied shortcut to wrong operand",
836
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Evaluate: 8528 + 3299 - 3298\n\nSolution: Using Near-cancellation: 3299 - 3298 = 1, so answer ≈ 8528 + 1.\nApproximation gives: 17058"
837
+ },
838
+ {
839
+ "task_id": "J2_equation_reasoning_000738",
840
+ "task_type": "J2_error_detection",
841
+ "category": "equation_reasoning",
842
+ "problem": "What value fills the blank? 4804 + 8180 = ___ + 5895",
843
+ "correct_answer": "7089",
844
+ "ns_solution_with_error": "Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 7092",
845
+ "error_type": "arithmetic_slip",
846
+ "error_description": "Arithmetic slip in the shortcut step",
847
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What value fills the blank? 4804 + 8180 = ___ + 5895\n\nSolution: Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 7092"
848
+ },
849
+ {
850
+ "task_id": "J2_landmark_comparison_000663",
851
+ "task_type": "J2_error_detection",
852
+ "category": "landmark_comparison",
853
+ "problem": "Is 10% of 75230 greater than 17577?",
854
+ "correct_answer": "No",
855
+ "ns_solution_with_error": "Using Use 10% as landmark: 10% of 75230 = 7523.\nApproximation gives: 7147",
856
+ "error_type": "wrong_rounding",
857
+ "error_description": "Rounded in the wrong direction",
858
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Is 10% of 75230 greater than 17577?\n\nSolution: Using Use 10% as landmark: 10% of 75230 = 7523.\nApproximation gives: 7147"
859
+ },
860
+ {
861
+ "task_id": "J2_structural_shortcuts_000484",
862
+ "task_type": "J2_error_detection",
863
+ "category": "structural_shortcuts",
864
+ "problem": "What is 10001 * 4007?",
865
+ "correct_answer": "40074007",
866
+ "ns_solution_with_error": "Using Use (10000+1)*m = 10000*m + 1*m.\nApproximation gives: 38070307",
867
+ "error_type": "wrong_rounding",
868
+ "error_description": "Rounded in the wrong direction",
869
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 10001 * 4007?\n\nSolution: Using Use (10000+1)*m = 10000*m + 1*m.\nApproximation gives: 38070307"
870
+ },
871
+ {
872
+ "task_id": "J2_compatible_numbers_000619",
873
+ "task_type": "J2_error_detection",
874
+ "category": "compatible_numbers",
875
+ "problem": "Estimate 1274 × 8677.",
876
+ "correct_answer": "11054498",
877
+ "ns_solution_with_error": "Using Round to 1250×8000 for easy mental computation.\nApproximation gives: 22108996",
878
+ "error_type": "wrong_operand",
879
+ "error_description": "Applied shortcut to wrong operand",
880
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Estimate 1274 × 8677.\n\nSolution: Using Round to 1250×8000 for easy mental computation.\nApproximation gives: 22108996"
881
+ },
882
+ {
883
+ "task_id": "J2_cancellation_identity_000558",
884
+ "task_type": "J2_error_detection",
885
+ "category": "cancellation_identity",
886
+ "problem": "Evaluate: 3344 + 1236 - 1234",
887
+ "correct_answer": "3346",
888
+ "ns_solution_with_error": "Using Near-cancellation: 1236 - 1234 = 2, so answer ≈ 3344 + 2.\nApproximation gives: 3342",
889
+ "error_type": "arithmetic_slip",
890
+ "error_description": "Arithmetic slip in the shortcut step",
891
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Evaluate: 3344 + 1236 - 1234\n\nSolution: Using Near-cancellation: 1236 - 1234 = 2, so answer ≈ 3344 + 2.\nApproximation gives: 3342"
892
+ },
893
+ {
894
+ "task_id": "J2_structural_shortcuts_000492",
895
+ "task_type": "J2_error_detection",
896
+ "category": "structural_shortcuts",
897
+ "problem": "What is 9998 * 2912?",
898
+ "correct_answer": "29114176",
899
+ "ns_solution_with_error": "Using Use (10000-2)*m = 10000*m - 2*m.\nApproximation gives: 21114176",
900
+ "error_type": "transcription_error",
901
+ "error_description": "Transcription error in final answer",
902
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 9998 * 2912?\n\nSolution: Using Use (10000-2)*m = 10000*m - 2*m.\nApproximation gives: 21114176"
903
+ },
904
+ {
905
+ "task_id": "J2_landmark_comparison_000699",
906
+ "task_type": "J2_error_detection",
907
+ "category": "landmark_comparison",
908
+ "problem": "Is 11% of 57250 greater than 11559?",
909
+ "correct_answer": "No",
910
+ "ns_solution_with_error": "Using Use 10% as landmark: 10% of 57250 = 5725.\nApproximation gives: 6497",
911
+ "error_type": "transcription_error",
912
+ "error_description": "Transcription error in final answer",
913
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Is 11% of 57250 greater than 11559?\n\nSolution: Using Use 10% as landmark: 10% of 57250 = 5725.\nApproximation gives: 6497"
914
+ },
915
+ {
916
+ "task_id": "J2_relative_distance_000506",
917
+ "task_type": "J2_error_detection",
918
+ "category": "relative_distance",
919
+ "problem": "Which is larger: 4901/9978 or 3743/7451?",
920
+ "correct_answer": "3743/7451",
921
+ "ns_solution_with_error": "Using One is below 1/2, the other above; no computation needed.\nApproximation gives: 1",
922
+ "error_type": "wrong_operand",
923
+ "error_description": "Applied shortcut to wrong operand",
924
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which is larger: 4901/9978 or 3743/7451?\n\nSolution: Using One is below 1/2, the other above; no computation needed.\nApproximation gives: 1"
925
+ },
926
+ {
927
+ "task_id": "J2_option_elimination_000786",
928
+ "task_type": "J2_error_detection",
929
+ "category": "option_elimination",
930
+ "problem": "What is 3972 × 8996?",
931
+ "correct_answer": "35732112",
932
+ "ns_solution_with_error": "Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 37732112",
933
+ "error_type": "transcription_error",
934
+ "error_description": "Transcription error in final answer",
935
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 3972 × 8996?\n\nSolution: Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 37732112"
936
+ },
937
+ {
938
+ "task_id": "J2_equation_reasoning_000708",
939
+ "task_type": "J2_error_detection",
940
+ "category": "equation_reasoning",
941
+ "problem": "What value fills the blank? 3791 + 6639 = ___ + 3553",
942
+ "correct_answer": "6877",
943
+ "ns_solution_with_error": "Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 6870",
944
+ "error_type": "transcription_error",
945
+ "error_description": "Transcription error in final answer",
946
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What value fills the blank? 3791 + 6639 = ___ + 3553\n\nSolution: Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 6870"
947
+ },
948
+ {
949
+ "task_id": "J2_equation_reasoning_000748",
950
+ "task_type": "J2_error_detection",
951
+ "category": "equation_reasoning",
952
+ "problem": "What value fills the blank? 3807 + 1362 + ___ = 1362 + 8347 + 3807",
953
+ "correct_answer": "8347",
954
+ "ns_solution_with_error": "Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 8352",
955
+ "error_type": "arithmetic_slip",
956
+ "error_description": "Arithmetic slip in the shortcut step",
957
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What value fills the blank? 3807 + 1362 + ___ = 1362 + 8347 + 3807\n\nSolution: Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 8352"
958
+ },
959
+ {
960
+ "task_id": "J2_structural_shortcuts_000453",
961
+ "task_type": "J2_error_detection",
962
+ "category": "structural_shortcuts",
963
+ "problem": "What is 10002 * 7131?",
964
+ "correct_answer": "71324262",
965
+ "ns_solution_with_error": "Using Use (10000+2)*m = 10000*m + 2*m.\nApproximation gives: 71324258",
966
+ "error_type": "arithmetic_slip",
967
+ "error_description": "Arithmetic slip in the shortcut step",
968
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 10002 * 7131?\n\nSolution: Using Use (10000+2)*m = 10000*m + 2*m.\nApproximation gives: 71324258"
969
+ },
970
+ {
971
+ "task_id": "J2_relative_distance_000532",
972
+ "task_type": "J2_error_detection",
973
+ "category": "relative_distance",
974
+ "problem": "Which is larger: 1971/3979 or 3695/7308?",
975
+ "correct_answer": "3695/7308",
976
+ "ns_solution_with_error": "Using One is below 1/2, the other above; no computation needed.\nApproximation gives: 1",
977
+ "error_type": "wrong_rounding",
978
+ "error_description": "Rounded in the wrong direction",
979
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which is larger: 1971/3979 or 3695/7308?\n\nSolution: Using One is below 1/2, the other above; no computation needed.\nApproximation gives: 1"
980
+ },
981
+ {
982
+ "task_id": "J2_compatible_numbers_000610",
983
+ "task_type": "J2_error_detection",
984
+ "category": "compatible_numbers",
985
+ "problem": "Estimate 1273 × 7425.",
986
+ "correct_answer": "9452025",
987
+ "ns_solution_with_error": "Using Round to 1250×8000 for easy mental computation.\nApproximation gives: 9452028",
988
+ "error_type": "arithmetic_slip",
989
+ "error_description": "Arithmetic slip in the shortcut step",
990
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Estimate 1273 × 7425.\n\nSolution: Using Round to 1250×8000 for easy mental computation.\nApproximation gives: 9452028"
991
+ },
992
+ {
993
+ "task_id": "J2_magnitude_estimation_000442",
994
+ "task_type": "J2_error_detection",
995
+ "category": "magnitude_estimation",
996
+ "problem": "Which of the following is the best estimate for 9800 * 9800?",
997
+ "correct_answer": "96040000",
998
+ "ns_solution_with_error": "Using Round both to 10000 and multiply.\nApproximation gives: 192080000",
999
+ "error_type": "wrong_operand",
1000
+ "error_description": "Applied shortcut to wrong operand",
1001
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which of the following is the best estimate for 9800 * 9800?\n\nSolution: Using Round both to 10000 and multiply.\nApproximation gives: 192080000"
1002
+ },
1003
+ {
1004
+ "task_id": "J2_landmark_comparison_000678",
1005
+ "task_type": "J2_error_detection",
1006
+ "category": "landmark_comparison",
1007
+ "problem": "Is 23% of 55000 greater than 22317?",
1008
+ "correct_answer": "No",
1009
+ "ns_solution_with_error": "Using Use 25% as landmark: 25% of 55000 = 13750.\nApproximation gives: 6325",
1010
+ "error_type": "wrong_operand",
1011
+ "error_description": "Applied shortcut to wrong operand",
1012
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Is 23% of 55000 greater than 22317?\n\nSolution: Using Use 25% as landmark: 25% of 55000 = 13750.\nApproximation gives: 6325"
1013
+ },
1014
+ {
1015
+ "task_id": "J2_landmark_comparison_000660",
1016
+ "task_type": "J2_error_detection",
1017
+ "category": "landmark_comparison",
1018
+ "problem": "Is 27% of 31870 greater than 12925?",
1019
+ "correct_answer": "No",
1020
+ "ns_solution_with_error": "Using Use 25% as landmark: 25% of 31870 = 7967.\nApproximation gives: 17209",
1021
+ "error_type": "wrong_operand",
1022
+ "error_description": "Applied shortcut to wrong operand",
1023
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Is 27% of 31870 greater than 12925?\n\nSolution: Using Use 25% as landmark: 25% of 31870 = 7967.\nApproximation gives: 17209"
1024
+ },
1025
+ {
1026
+ "task_id": "J2_equation_reasoning_000726",
1027
+ "task_type": "J2_error_detection",
1028
+ "category": "equation_reasoning",
1029
+ "problem": "What value fills the blank? 1264 + 1118 = ___ + 7226",
1030
+ "correct_answer": "-4844",
1031
+ "ns_solution_with_error": "Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: -4854",
1032
+ "error_type": "transcription_error",
1033
+ "error_description": "Transcription error in final answer",
1034
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What value fills the blank? 1264 + 1118 = ___ + 7226\n\nSolution: Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: -4854"
1035
+ },
1036
+ {
1037
+ "task_id": "J2_relative_distance_000524",
1038
+ "task_type": "J2_error_detection",
1039
+ "category": "relative_distance",
1040
+ "problem": "Which is larger: 1837/3735 or 2765/5491?",
1041
+ "correct_answer": "2765/5491",
1042
+ "ns_solution_with_error": "Using One is below 1/2, the other above; no computation needed.\nApproximation gives: 0",
1043
+ "error_type": "wrong_rounding",
1044
+ "error_description": "Rounded in the wrong direction",
1045
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which is larger: 1837/3735 or 2765/5491?\n\nSolution: Using One is below 1/2, the other above; no computation needed.\nApproximation gives: 0"
1046
+ },
1047
+ {
1048
+ "task_id": "J2_relative_distance_000546",
1049
+ "task_type": "J2_error_detection",
1050
+ "category": "relative_distance",
1051
+ "problem": "Which is larger: 3607/7251 or 2876/5669?",
1052
+ "correct_answer": "2876/5669",
1053
+ "ns_solution_with_error": "Using One is below 1/2, the other above; no computation needed.\nApproximation gives: -2",
1054
+ "error_type": "arithmetic_slip",
1055
+ "error_description": "Arithmetic slip in the shortcut step",
1056
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which is larger: 3607/7251 or 2876/5669?\n\nSolution: Using One is below 1/2, the other above; no computation needed.\nApproximation gives: -2"
1057
+ },
1058
+ {
1059
+ "task_id": "J2_option_elimination_000792",
1060
+ "task_type": "J2_error_detection",
1061
+ "category": "option_elimination",
1062
+ "problem": "What is 4893 × 1523?",
1063
+ "correct_answer": "7452039",
1064
+ "ns_solution_with_error": "Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 14904078",
1065
+ "error_type": "wrong_operand",
1066
+ "error_description": "Applied shortcut to wrong operand",
1067
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 4893 × 1523?\n\nSolution: Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 14904078"
1068
+ },
1069
+ {
1070
+ "task_id": "J2_cancellation_identity_000554",
1071
+ "task_type": "J2_error_detection",
1072
+ "category": "cancellation_identity",
1073
+ "problem": "Evaluate: 6105 + 3719 - 3720",
1074
+ "correct_answer": "6104",
1075
+ "ns_solution_with_error": "Using Near-cancellation: 3719 - 3720 = -1, so answer ≈ 6105 + -1.\nApproximation gives: 6409",
1076
+ "error_type": "wrong_rounding",
1077
+ "error_description": "Rounded in the wrong direction",
1078
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Evaluate: 6105 + 3719 - 3720\n\nSolution: Using Near-cancellation: 3719 - 3720 = -1, so answer ≈ 6105 + -1.\nApproximation gives: 6409"
1079
+ },
1080
+ {
1081
+ "task_id": "J2_option_elimination_000789",
1082
+ "task_type": "J2_error_detection",
1083
+ "category": "option_elimination",
1084
+ "problem": "What is 3121 × 1321?",
1085
+ "correct_answer": "4122841",
1086
+ "ns_solution_with_error": "Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 4122838",
1087
+ "error_type": "arithmetic_slip",
1088
+ "error_description": "Arithmetic slip in the shortcut step",
1089
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 3121 × 1321?\n\nSolution: Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 4122838"
1090
+ },
1091
+ {
1092
+ "task_id": "J2_equation_reasoning_000717",
1093
+ "task_type": "J2_error_detection",
1094
+ "category": "equation_reasoning",
1095
+ "problem": "What value fills the blank? 6336 + 4267 = ___ + 4522",
1096
+ "correct_answer": "6081",
1097
+ "ns_solution_with_error": "Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 3040",
1098
+ "error_type": "wrong_operand",
1099
+ "error_description": "Applied shortcut to wrong operand",
1100
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What value fills the blank? 6336 + 4267 = ___ + 4522\n\nSolution: Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 3040"
1101
+ },
1102
+ {
1103
+ "task_id": "J2_relative_distance_000533",
1104
+ "task_type": "J2_error_detection",
1105
+ "category": "relative_distance",
1106
+ "problem": "Which is larger: 3415/6937 or 4397/8764?",
1107
+ "correct_answer": "4397/8764",
1108
+ "ns_solution_with_error": "Using One is below 1/2, the other above; no computation needed.\nApproximation gives: 5",
1109
+ "error_type": "arithmetic_slip",
1110
+ "error_description": "Arithmetic slip in the shortcut step",
1111
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which is larger: 3415/6937 or 4397/8764?\n\nSolution: Using One is below 1/2, the other above; no computation needed.\nApproximation gives: 5"
1112
+ },
1113
+ {
1114
+ "task_id": "J2_cancellation_identity_000566",
1115
+ "task_type": "J2_error_detection",
1116
+ "category": "cancellation_identity",
1117
+ "problem": "Evaluate: 7556 + 4084 - 4086",
1118
+ "correct_answer": "7554",
1119
+ "ns_solution_with_error": "Using Near-cancellation: 4084 - 4086 = -2, so answer ≈ 7556 + -2.\nApproximation gives: 7555",
1120
+ "error_type": "arithmetic_slip",
1121
+ "error_description": "Arithmetic slip in the shortcut step",
1122
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Evaluate: 7556 + 4084 - 4086\n\nSolution: Using Near-cancellation: 4084 - 4086 = -2, so answer ≈ 7556 + -2.\nApproximation gives: 7555"
1123
+ },
1124
+ {
1125
+ "task_id": "J2_option_elimination_000772",
1126
+ "task_type": "J2_error_detection",
1127
+ "category": "option_elimination",
1128
+ "problem": "What is 2726 × 5890?",
1129
+ "correct_answer": "16056140",
1130
+ "ns_solution_with_error": "Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 8028070",
1131
+ "error_type": "wrong_operand",
1132
+ "error_description": "Applied shortcut to wrong operand",
1133
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 2726 × 5890?\n\nSolution: Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 8028070"
1134
+ },
1135
+ {
1136
+ "task_id": "J2_landmark_comparison_000669",
1137
+ "task_type": "J2_error_detection",
1138
+ "category": "landmark_comparison",
1139
+ "problem": "Is 27% of 18930 greater than 6267?",
1140
+ "correct_answer": "No",
1141
+ "ns_solution_with_error": "Using Use 25% as landmark: 25% of 18930 = 4732.\nApproximation gives: 5116",
1142
+ "error_type": "arithmetic_slip",
1143
+ "error_description": "Arithmetic slip in the shortcut step",
1144
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Is 27% of 18930 greater than 6267?\n\nSolution: Using Use 25% as landmark: 25% of 18930 = 4732.\nApproximation gives: 5116"
1145
+ },
1146
+ {
1147
+ "task_id": "J2_magnitude_estimation_000401",
1148
+ "task_type": "J2_error_detection",
1149
+ "category": "magnitude_estimation",
1150
+ "problem": "Which of the following is the best estimate for 10200 * 10100?",
1151
+ "correct_answer": "103020000",
1152
+ "ns_solution_with_error": "Using Round both to 10000 and multiply.\nApproximation gives: 51510000",
1153
+ "error_type": "wrong_operand",
1154
+ "error_description": "Applied shortcut to wrong operand",
1155
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which of the following is the best estimate for 10200 * 10100?\n\nSolution: Using Round both to 10000 and multiply.\nApproximation gives: 51510000"
1156
+ },
1157
+ {
1158
+ "task_id": "J2_compatible_numbers_000625",
1159
+ "task_type": "J2_error_detection",
1160
+ "category": "compatible_numbers",
1161
+ "problem": "Estimate 4910 × 1977.",
1162
+ "correct_answer": "9707070",
1163
+ "ns_solution_with_error": "Using Round to 5000×2000 for easy mental computation.\nApproximation gives: 9221717",
1164
+ "error_type": "wrong_rounding",
1165
+ "error_description": "Rounded in the wrong direction",
1166
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Estimate 4910 × 1977.\n\nSolution: Using Round to 5000×2000 for easy mental computation.\nApproximation gives: 9221717"
1167
+ },
1168
+ {
1169
+ "task_id": "J2_cancellation_identity_000600",
1170
+ "task_type": "J2_error_detection",
1171
+ "category": "cancellation_identity",
1172
+ "problem": "Evaluate: 2704 + 1588 - 1586",
1173
+ "correct_answer": "2706",
1174
+ "ns_solution_with_error": "Using Near-cancellation: 1588 - 1586 = 2, so answer ≈ 2704 + 2.\nApproximation gives: 2571",
1175
+ "error_type": "wrong_rounding",
1176
+ "error_description": "Rounded in the wrong direction",
1177
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Evaluate: 2704 + 1588 - 1586\n\nSolution: Using Near-cancellation: 1588 - 1586 = 2, so answer ≈ 2704 + 2.\nApproximation gives: 2571"
1178
+ },
1179
+ {
1180
+ "task_id": "J2_magnitude_estimation_000426",
1181
+ "task_type": "J2_error_detection",
1182
+ "category": "magnitude_estimation",
1183
+ "problem": "Which of the following is the best estimate for 10200 * 9900?",
1184
+ "correct_answer": "100980000",
1185
+ "ns_solution_with_error": "Using Round both to 10000 and multiply.\nApproximation gives: 100980004",
1186
+ "error_type": "arithmetic_slip",
1187
+ "error_description": "Arithmetic slip in the shortcut step",
1188
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which of the following is the best estimate for 10200 * 9900?\n\nSolution: Using Round both to 10000 and multiply.\nApproximation gives: 100980004"
1189
+ },
1190
+ {
1191
+ "task_id": "J2_compatible_numbers_000648",
1192
+ "task_type": "J2_error_detection",
1193
+ "category": "compatible_numbers",
1194
+ "problem": "Estimate 2520 × 3623.",
1195
+ "correct_answer": "9129960",
1196
+ "ns_solution_with_error": "Using Round to 2500×4000 for easy mental computation.\nApproximation gives: 9129962",
1197
+ "error_type": "arithmetic_slip",
1198
+ "error_description": "Arithmetic slip in the shortcut step",
1199
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Estimate 2520 × 3623.\n\nSolution: Using Round to 2500×4000 for easy mental computation.\nApproximation gives: 9129962"
1200
+ },
1201
+ {
1202
+ "task_id": "J2_option_elimination_000760",
1203
+ "task_type": "J2_error_detection",
1204
+ "category": "option_elimination",
1205
+ "problem": "What is 5927 × 1249?",
1206
+ "correct_answer": "7402823",
1207
+ "ns_solution_with_error": "Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 7402824",
1208
+ "error_type": "arithmetic_slip",
1209
+ "error_description": "Arithmetic slip in the shortcut step",
1210
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 5927 × 1249?\n\nSolution: Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 7402824"
1211
+ },
1212
+ {
1213
+ "task_id": "J2_equation_reasoning_000716",
1214
+ "task_type": "J2_error_detection",
1215
+ "category": "equation_reasoning",
1216
+ "problem": "What value fills the blank? 7447 + 7834 = ___ + 1092",
1217
+ "correct_answer": "14189",
1218
+ "ns_solution_with_error": "Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 14184",
1219
+ "error_type": "arithmetic_slip",
1220
+ "error_description": "Arithmetic slip in the shortcut step",
1221
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What value fills the blank? 7447 + 7834 = ___ + 1092\n\nSolution: Using Recognize commutativity/distributive law — matching terms cancel.\nApproximation gives: 14184"
1222
+ },
1223
+ {
1224
+ "task_id": "J2_compatible_numbers_000617",
1225
+ "task_type": "J2_error_detection",
1226
+ "category": "compatible_numbers",
1227
+ "problem": "Estimate 4966 × 1988.",
1228
+ "correct_answer": "9872408",
1229
+ "ns_solution_with_error": "Using Round to 5000×2000 for easy mental computation.\nApproximation gives: 9378788",
1230
+ "error_type": "wrong_rounding",
1231
+ "error_description": "Rounded in the wrong direction",
1232
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Estimate 4966 × 1988.\n\nSolution: Using Round to 5000×2000 for easy mental computation.\nApproximation gives: 9378788"
1233
+ },
1234
+ {
1235
+ "task_id": "J2_compatible_numbers_000633",
1236
+ "task_type": "J2_error_detection",
1237
+ "category": "compatible_numbers",
1238
+ "problem": "Estimate 4960 × 2196.",
1239
+ "correct_answer": "10892160",
1240
+ "ns_solution_with_error": "Using Round to 5000×2000 for easy mental computation.\nApproximation gives: 5446080",
1241
+ "error_type": "wrong_operand",
1242
+ "error_description": "Applied shortcut to wrong operand",
1243
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Estimate 4960 × 2196.\n\nSolution: Using Round to 5000×2000 for easy mental computation.\nApproximation gives: 5446080"
1244
+ },
1245
+ {
1246
+ "task_id": "J2_option_elimination_000776",
1247
+ "task_type": "J2_error_detection",
1248
+ "category": "option_elimination",
1249
+ "problem": "What is 6135 × 7717?",
1250
+ "correct_answer": "47343795",
1251
+ "ns_solution_with_error": "Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 47343705",
1252
+ "error_type": "transcription_error",
1253
+ "error_description": "Transcription error in final answer",
1254
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 6135 × 7717?\n\nSolution: Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 47343705"
1255
+ },
1256
+ {
1257
+ "task_id": "J2_magnitude_estimation_000403",
1258
+ "task_type": "J2_error_detection",
1259
+ "category": "magnitude_estimation",
1260
+ "problem": "Which of the following is the best estimate for 10200 * 10200?",
1261
+ "correct_answer": "104040000",
1262
+ "ns_solution_with_error": "Using Round both to 10000 and multiply.\nApproximation gives: 98838000",
1263
+ "error_type": "wrong_rounding",
1264
+ "error_description": "Rounded in the wrong direction",
1265
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which of the following is the best estimate for 10200 * 10200?\n\nSolution: Using Round both to 10000 and multiply.\nApproximation gives: 98838000"
1266
+ },
1267
+ {
1268
+ "task_id": "J2_cancellation_identity_000583",
1269
+ "task_type": "J2_error_detection",
1270
+ "category": "cancellation_identity",
1271
+ "problem": "Evaluate: 7896 + 2453 - 2454",
1272
+ "correct_answer": "7895",
1273
+ "ns_solution_with_error": "Using Near-cancellation: 2453 - 2454 = -1, so answer ≈ 7896 + -1.\nApproximation gives: 3947",
1274
+ "error_type": "wrong_operand",
1275
+ "error_description": "Applied shortcut to wrong operand",
1276
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Evaluate: 7896 + 2453 - 2454\n\nSolution: Using Near-cancellation: 2453 - 2454 = -1, so answer ≈ 7896 + -1.\nApproximation gives: 3947"
1277
+ },
1278
+ {
1279
+ "task_id": "J2_compatible_numbers_000650",
1280
+ "task_type": "J2_error_detection",
1281
+ "category": "compatible_numbers",
1282
+ "problem": "Estimate 4925 × 2150.",
1283
+ "correct_answer": "10588750",
1284
+ "ns_solution_with_error": "Using Round to 5000×2000 for easy mental computation.\nApproximation gives: 10588752",
1285
+ "error_type": "transcription_error",
1286
+ "error_description": "Transcription error in final answer",
1287
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Estimate 4925 × 2150.\n\nSolution: Using Round to 5000×2000 for easy mental computation.\nApproximation gives: 10588752"
1288
+ },
1289
+ {
1290
+ "task_id": "J2_magnitude_estimation_000443",
1291
+ "task_type": "J2_error_detection",
1292
+ "category": "magnitude_estimation",
1293
+ "problem": "Which of the following is the best estimate for 9800 * 9800?",
1294
+ "correct_answer": "96040000",
1295
+ "ns_solution_with_error": "Using Round both to 10000 and multiply.\nApproximation gives: 96040001",
1296
+ "error_type": "arithmetic_slip",
1297
+ "error_description": "Arithmetic slip in the shortcut step",
1298
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Which of the following is the best estimate for 9800 * 9800?\n\nSolution: Using Round both to 10000 and multiply.\nApproximation gives: 96040001"
1299
+ },
1300
+ {
1301
+ "task_id": "J2_option_elimination_000788",
1302
+ "task_type": "J2_error_detection",
1303
+ "category": "option_elimination",
1304
+ "problem": "What is 2243 × 8255?",
1305
+ "correct_answer": "18515965",
1306
+ "ns_solution_with_error": "Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 18515967",
1307
+ "error_type": "arithmetic_slip",
1308
+ "error_description": "Arithmetic slip in the shortcut step",
1309
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: What is 2243 × 8255?\n\nSolution: Using Check trailing digit / parity / magnitude — only one option matches.\nApproximation gives: 18515967"
1310
+ },
1311
+ {
1312
+ "task_id": "J2_landmark_comparison_000664",
1313
+ "task_type": "J2_error_detection",
1314
+ "category": "landmark_comparison",
1315
+ "problem": "Is 24% of 44600 greater than 13866?",
1316
+ "correct_answer": "No",
1317
+ "ns_solution_with_error": "Using Use 25% as landmark: 25% of 44600 = 11150.\nApproximation gives: 10707",
1318
+ "error_type": "arithmetic_slip",
1319
+ "error_description": "Arithmetic slip in the shortcut step",
1320
+ "prompt": "This solution attempts to use a number sense shortcut. Find the error and explain what went wrong.\n\nProblem: Is 24% of 44600 greater than 13866?\n\nSolution: Using Use 25% as landmark: 25% of 44600 = 11150.\nApproximation gives: 10707"
1321
+ }
1322
+ ]