---
language:
  - en
license: apache-2.0
base_model: Qwen/Qwen2.5-0.5B-Instruct
tags:
  - qwen2.5
  - math
  - reasoning
  - grpo
  - reinforcement-learning
  - unsloth
  - gsm8k
  - structured-output
datasets:
  - openai/gsm8k
  - open-r1/OpenR1-Math-220k
pipeline_tag: text-generation
library_name: transformers
---

# Q-SS-0.5B-Reasoning-Math

> *A compact, fast, and structured mathematical reasoning model — built to think before it answers.*

**Q-SS-0.5B-Reasoning-Math** is a fine-tuned version of [Qwen/Qwen2.5-0.5B-Instruct](https://huggingface.co/Qwen/Qwen2.5-0.5B-Instruct), trained using **Group Relative Policy Optimization (GRPO)** reinforcement learning — the same technique behind DeepSeek-R1. The model is designed to reason explicitly and transparently through mathematical problems before producing a clean, parseable final answer.

> 💾 Looking for the lightweight CPU version? See [Q-SS-0.5B-Reasoning-Math-GGUF](https://huggingface.co/saadxsalman/Q-SS-0.5B-Reasoning-Math-GGUF) for the Q4_K_M quantized model (~300MB).

---

## ✨ Highlights

- 🧠 **Thinks out loud** — explicit step-by-step reasoning inside `<thought>` tags before every answer
- 🎯 **Clean structured output** — final answer always isolated in `<answer>` tags, trivial to parse
- 🔁 **RL-trained** — learned through reward signals, not just imitation
- 🔧 **Fine-tunable** — full FP16 weights, ready for further training or fine-tuning
- 🔓 **Apache 2.0** — free for personal and commercial use

---

## 📋 Model Details

| Property | Details |
|---|---|
| **Model Name** | Q-SS-0.5B-Reasoning-Math |
| **Base Model** | Qwen/Qwen2.5-0.5B-Instruct |
| **Parameters** | 500M |
| **Training Method** | SFT Warm-up + GRPO Reinforcement Learning |
| **Trained On** | GSM8K + OpenR1-Math-220k |
| **Precision** | FP16 (merged, no adapter needed) |
| **License** | Apache 2.0 |
| **Developer** | Saad Salman |

---

## 💬 Output Format

Every response follows this strict structure:

```
<thought>
[Step-by-step reasoning and calculations]
</thought>
<answer>
[Final numerical answer only]
</answer>
```

---

## 🚀 Quick Start

```python
from transformers import AutoModelForCausalLM, AutoTokenizer
import torch

model_name = "saadxsalman/Q-SS-0.5B-Reasoning-Math"

tokenizer = AutoTokenizer.from_pretrained(model_name)
model = AutoModelForCausalLM.from_pretrained(
    model_name,
    torch_dtype = torch.float16,
    device_map  = "auto",
)

SYSTEM_PROMPT = \"\"\"You are a mathematical reasoning engine.
Solve the problem step-by-step inside <thought> tags, then give ONLY the
final numerical or LaTeX result inside <answer> tags.

<thought>
[Your internal reasoning and calculations here]
</thought>
<answer>
[Final answer only]
</answer>\"\"\"

def solve(problem):
    messages = [
        {"role": "system", "content": SYSTEM_PROMPT},
        {"role": "user",   "content": problem},
    ]
    inputs = tokenizer.apply_chat_template(
        messages,
        tokenize              = True,
        add_generation_prompt = True,
        return_tensors        = "pt",
    ).to(model.device)

    with torch.no_grad():
        outputs = model.generate(
            input_ids      = inputs,
            max_new_tokens = 384,
            temperature    = 0.1,
            do_sample      = True,
            pad_token_id   = tokenizer.eos_token_id,
        )

    response = tokenizer.decode(outputs[0], skip_special_tokens=True)
    if "<answer>" in response:
        return response.split("<answer>")[-1].split("</answer>")[0].strip()
    return response

print(solve("Janet has 3 cats. Each cat eats 2 cans of food per day. How many cans does she need for 7 days?"))
# Output: 42
```

---

## 📝 Example Outputs

**Problem:** Janet has 3 cats. Each cat eats 2 cans of food per day. How many cans does she need for 7 days?

```
<thought>
Each cat eats 2 cans per day.
Janet has 3 cats, so they eat 3 × 2 = 6 cans per day together.
For 7 days: 6 × 7 = 42 cans total.
</thought>
<answer>
42
</answer>
```

**Problem:** Tom has $50. He buys a book for $12 and a pen for $3. How much money does he have left?

```
<thought>
Tom starts with $50.
He spends $12 on a book and $3 on a pen.
Total spent: 12 + 3 = $15.
Money remaining: 50 - 15 = $35.
</thought>
<answer>
35
</answer>
```

---

## ✅ What It's Good At

| Problem Type | Support |
|---|---|
| Basic arithmetic | ✅ Reliable |
| Multi-step word problems | ✅ Reliable |
| Problems with units and currency | ✅ Reliable |
| Basic algebra | ⚠️ Partial |
| Competition math (AMC/AIME) | ❌ Beyond capacity |

---

## 📦 Related Models

| Repo | Format | Size | Best For |
|---|---|---|---|
| [Q-SS-0.5B-Reasoning-Math](https://huggingface.co/saadxsalman/Q-SS-0.5B-Reasoning-Math) | FP16 | ~988MB | GPU inference & further fine-tuning |
| [Q-SS-0.5B-Reasoning-Math-GGUF](https://huggingface.co/saadxsalman/Q-SS-0.5B-Reasoning-Math-GGUF) | Q4_K_M | ~300MB | Local CPU inference |

---

## ⚠️ Limitations

- Optimized for English language math problems only
- Complex abstract reasoning, geometry, and calculus are beyond reliable capacity at 0.5B scale
- Always verify critical calculations — the model may occasionally produce confident but incorrect answers

---

## 🙏 Acknowledgements

- [Unsloth](https://github.com/unslothai/unsloth) — efficient fine-tuning framework
- [Qwen Team](https://huggingface.co/Qwen) — Qwen2.5-0.5B-Instruct base model
- [HuggingFace TRL](https://github.com/huggingface/trl) — GRPO implementation
- [OpenR1](https://huggingface.co/open-r1) — OpenR1-Math-220k dataset
- [OpenAI](https://huggingface.co/openai) — GSM8K dataset

---

## 📄 Citation

```bibtex
@misc{qss-reasoning-math-2025,
  author       = {Saad Salman},
  title        = {Q-SS-0.5B-Reasoning-Math},
  year         = {2025},
  publisher    = {HuggingFace},
  howpublished = {\\url{https://huggingface.co/saadxsalman/Q-SS-0.5B-Reasoning-Math}},
}
```