Does “let’s think step by step” actually help?

Category: LLM & Prompt Engineering

Answer

Yes, for reasoning-heavy tasks. The model’s intermediate reasoning improves final answer quality because it forces the model to commit before committing. Zero-shot CoT (“think step by step”) is a single line; few-shot CoT (3 worked examples with reasoning) is much stronger. Trade-off: tokens spent on reasoning are tokens not in the answer.

Concrete examples from the fca project context

Example 1

“Let’s think step by step. [reasoning]. Therefore the answer is X.”

Example 2

Few-shot CoT: provide 3 examples with explicit reasoning chains.

Example 3

For math / logic puzzles, CoT is mandatory. For rote classification, CoT adds tokens without gain.

Data flow / flow chart

standard prompt -> answer
"think step by step" -> reasoning -> answer
few-shot CoT    -> examples + reasoning -> answer

Takeaway

CoT for reasoning tasks. Skip CoT for classification/extraction where tokens get wasted.