Rularoo

Guess the rule, not the answer.

You are shown three numbers. They follow a rule. Find it.

Rularoo is a daily deduction game built on Peter Wason's 2-4-6 task, the experiment that showed people look for evidence that confirms them and almost never for evidence that would prove them wrong.

Play today's puzzle Learn the rules

Today the game opens with something like

  1. 2
  2. 4
  3. 6

Most people guess "add two each time". Most people are wrong, and every test they run says FITS.

Why it is harder than it looks

The rule people reach for is almost always narrower than the real one. A narrower rule only accepts sequences the real rule also accepts, so every sequence you test to confirm your idea comes back FITS. Confirmation cannot get you out. The probe that frees you is one you expected to fail.

Three puzzles a day

Easy

Three terms, 1 to 30. A gentle vocabulary and par of two to five probes.

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Medium

Three terms, -20 to 99. Negative numbers, sums and gaps come into play.

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Hard

Four terms and rules that combine two conditions. Par runs to twelve.

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