Show your work
When a model jumps straight to an answer, you get a number or a verdict you can't check. Chain-of-thought (CoT) prompting asks it to reason through the problem step by step first. Two things improve:
- You can check it. Each step is visible, so a wrong turn is easy to spot.
- It's more reliable on hard problems. Writing out intermediate steps gives the model's later predictions something solid to build on.
The same problem, both ways
Direct: "A store has 150 apples. It sells 40% on Monday, receives 30 more on Tuesday, and sells a third of its stock on Wednesday. How many apples are left? Answer with a number." You get a number, perhaps 80, and no way to know if it's right without doing the maths yourself.
Chain-of-thought: the same problem, plus "Work through it one day at a time, showing the count after each day. Then give the final answer on its own line."
- Monday: 40% of 150 is 60 sold, so 90 left.
- Tuesday: 90 + 30 = 120.
- Wednesday: a third of 120 is 40 sold, so 80 left.
Final answer: 80 apples. Now every step can be checked.
When to use it
- Multi-step maths and estimates: pricing, budgets, timelines
- Plans and decisions: "compare these three options against my criteria, then recommend one"
- Diagnosis: "list the likely causes, rule each one in or out, then give the most likely"
For simple tasks (rewrite this sentence, translate this paragraph) it just adds length.
Phrasing that works
- "Think through this step by step before answering."
- "First list the facts you're using. Then reason through them. Then answer."
- "Show your working, then put the final answer on its own line."
The last one is handy when you want to reuse the answer: the reasoning is there to check, and the answer is easy to find. Some models reason internally before replying; asking for visible steps still helps you check the result.
Try it
Take a real decision you're weighing, such as two tools, two offers, or two schedules. In Ask Ace, ask for a recommendation directly, then again with a chain-of-thought instruction. Which answer would you trust? The lab is next.
Before and after
Before
Prompt
A store has 150 apples. It sells 40% on Monday, receives 30 more on Tuesday, and sells a third of its stock on Wednesday. How many apples are left? Answer with a number.
Output
80
After
Prompt
A store has 150 apples. It sells 40% on Monday, receives 30 more on Tuesday, and sells a third of its stock on Wednesday. How many apples are left? Work through it one day at a time, showing the count after each day. Then give the final answer on its own line.
Output
Monday: 40% of 150 is 60 sold, so 150 − 60 = 90. Tuesday: 90 + 30 = 120. Wednesday: a third of 120 is 40 sold, so 120 − 40 = 80. Final answer: 80 apples
Both answers are right here, but only the second can be checked. On harder problems, writing out the steps also makes a wrong step less likely.