How to play
- Read the rule at the top before inspecting the values.
- Select the one value that does not satisfy that rule.
- Read the explanation, including why the other values belong together.
What this game practices
The explicit rule keeps the task evidence-based instead of relying on an unstated pattern. A richer follow-up is to ask whether a different defensible rule could classify the same numbers another way.
How we checked it
Original coolmath game. Every reviewed set names its intended rule—such as factors, multiples, parity, or square numbers—and contains exactly one exception to that rule.
Reviewed by coolmath Editorial Team · Updated 2026-09-20