Reasoning Models Explained: What Changes When AI Thinks First

Business Pill 30 · When a model thinks before it answers

A reasoning model spends extra effort at the moment of the question. Better answers can now be bought with more compute at the moment of use.

A short explainer video. The numbers in it are round numbers for illustration.

The Short Answer

A standard model answers immediately. It reads the question and starts writing. That works for simple requests. But on a hard problem, the first thing that comes to mind is often wrong.

What Reasoning Is

A reasoning model does something different. Before answering, it works through the problem step by step. It tries an approach, checks it, changes course if needed, and only then does it answer.

This is called reasoning, or sometimes thinking. The model spends extra effort at the moment of the question.

A Worked Example

That thinking is not free. It is made of tokens. The model writes out its working, and you pay for every word of it, even though you may never see it.

With round numbers: a quick answer uses 500 tokens and takes two seconds. A reasoned answer may use 5,000 and take 30 seconds. That is 10 times the cost and 15 times the wait, for an answer that is right more often.

Bar chart: a quick answer uses 500 tokens and a reasoned answer 5,000 tokens
Ten times the tokens and fifteen times the wait for an answer that is right more often. Round numbers for illustration.

A Choice, Task by Task

For a greeting or a simple lookup, reasoning is waste. For planning, analysis or code, it is often worth every token. The skill is matching the effort to the problem.

And this changes the economics. Better answers can now be bought with more compute at the moment of use, not only with a bigger model.

Three Questions to Ask

  1. How hard is this task really?
  2. What is a better answer worth?
  3. How long can the user wait?

How This Concept Connects

Layer 2 of 8 · Models & Training, on the Business Engineer Concept Map

  • Hidden Reasoning builds on Reasoning Models. Hidden reasoning is the private working a model does before it answers, the step-by-step thinking reasoning models add.
  • Reasoning Models is priced by Tokens. Reasoning is made of tokens: you pay for every word of the working, even when you never see it.
  • Reasoning Models contrasts with Model Routing. Both match effort to difficulty: reasoning spends more thinking on hard tasks, routing sends easy ones to a cheaper model.
Business Engineer framework
Tokenomics: The Economics of AI
Reasoning tokens change cost per answer.
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