Hard
Deduction Riddles
25 XP

The Four Card Problem

5,916 solved 81% solve rate 19% fail rate
Four cards show A, K, 4, 7. Rule: If a card has a vowel on one side, it must have an even number on the other. Which cards must you flip to test this rule?
Only 81% solve this correctly
5,916 attempts
Earn +25 XP for solving
Quick Answer & Explanation
Flip A

The answer to this riddle is Flip A. Difficulty: Hard · Solved by 5,916 puzzle lovers.

Flip A (to check for even number) and 7 (to check it does not have a vowel). K and 4 are irrelevant.
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