The 100 Prisoners Hat

3,025 solved 60% solve rate 40% fail rate

100 prisoners wear black or white hats. Each sees hats in front, not own. Starting from back, how can 99 guaranteed survive?

Only 60% solve this correctly

3,025 attempts

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Quick Answer & Explanation

Parity counting

The answer to this riddle is Parity counting. Difficulty: Hard · Solved by 3,025 puzzle lovers.