# Chain-of-thought prompting: make the model show its reasoning

> How to elicit step-by-step reasoning to improve accuracy on complex tasks.

Source: Promptea — https://www.promptea.me/en/guides/chain-of-thought · Language: English · Last updated: 2026-11-09

## When it helps

- Multi-step math, logic, or planning where errors compound.
- Any task where intermediate steps matter, not just the final answer.
- Debugging decisions: seeing the chain lets you spot exactly where reasoning broke.

## How to trigger it

- Add 'Think step by step before answering.' to any prompt.
- Or ask for a scratchpad: 'First, reason through it. Then give the final answer.'
- For structured output, separate the reasoning block from the answer block with tags.
- Ask it to check its own reasoning before committing to the answer.

## Before → after: a multi-step problem

- Before: "A subscription costs 12 per month with a 25% discount on annual billing. Is annual cheaper over 18 months?" The model may answer in one hop and slip on the arithmetic.
- After: "...Work through it step by step inside <reasoning>: price per month, annual price after discount, cost of each option over 18 months. Then give only the comparison inside <answer>. Re-check the arithmetic before answering."
- What changed: the intermediate quantities are computed explicitly and the answer is kept apart from the working, so errors are visible and the answer is easy to read.

## When not to use it

- Simple lookups, classification and rewriting rarely benefit: the steps add length and cost without improving the answer.
- Models that reason internally often need no 'think step by step' instruction, and heavy process instructions can interfere. Check the provider's guidance and the guide on reasoning models.
- Do not treat the written reasoning as a faithful trace of what the model computed. It is useful for spotting mistakes, not a guarantee of correctness: verify the final answer independently when it matters.

## Templates

### Step-by-step reasoning (general)

```text
Problem: [describe the task or question]

Think step by step:
1. Restate what is being asked.
2. Identify what information is known vs. what is missing.
3. Work through the logic in small steps.
4. State your conclusion.

Format:
<reasoning>
[steps here]
</reasoning>
<answer>
[final answer only]
</answer>
```

[Open in Promptea](https://www.promptea.me/en/analyzer?prompt=Problem%3A+%5Bdescribe+the+task+or+question%5D%0A%0AThink+step+by+step%3A%0A1.+Restate+what+is+being+asked.%0A2.+Identify+what+information+is+known+vs.+what+is+missing.%0A3.+Work+through+the+logic+in+small+steps.%0A4.+State+your+conclusion.%0A%0AFormat%3A%0A%3Creasoning%3E%0A%5Bsteps+here%5D%0A%3C%2Freasoning%3E%0A%3Canswer%3E%0A%5Bfinal+answer+only%5D%0A%3C%2Fanswer%3E&purpose=text&target=claude)

### Decision audit (spot the error)

```text
Review this decision chain and find the first point where the reasoning breaks down.

Decision:
"""[paste reasoning or plan]"""

Do this:
1. Restate each step in one sentence.
2. Mark the first step you believe is wrong or unsupported.
3. Explain why and propose a fix.
```

[Open in Promptea](https://www.promptea.me/en/analyzer?prompt=Review+this+decision+chain+and+find+the+first+point+where+the+reasoning+breaks+down.%0A%0ADecision%3A%0A%22%22%22%5Bpaste+reasoning+or+plan%5D%22%22%22%0A%0ADo+this%3A%0A1.+Restate+each+step+in+one+sentence.%0A2.+Mark+the+first+step+you+believe+is+wrong+or+unsupported.%0A3.+Explain+why+and+propose+a+fix.&purpose=text&target=gpt)

## Frequently asked questions

### Does chain-of-thought always help?

No. For simple tasks it adds noise and wastes tokens. Use it for tasks with multiple logical steps where order matters.

### What if I need a short final answer?

Separate reasoning from the answer with tags or sections. Ask for the reasoning first, then a single-sentence conclusion.

### Should I show the reasoning to my users?

Usually not. Keep reasoning and answer in separate blocks, show only the answer, and use the reasoning for debugging and review.

### Is chain-of-thought the same as prompt chaining?

No. Chain-of-thought happens inside one response; prompt chaining splits a task across several requests that you control. See the prompt chaining guide.