Moving stacked disks between three pegs without putting a larger disk on a smaller one takes at least 2ⁿ − 1 moves in this puzzle.

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Math & LogicOne small aha

Your new ahaThe Tower of Hanoi

The Tower of Hanoi: A disk-transfer puzzle with three pegs and a rule against placing a larger disk on a smaller one. Source: Tower of Hanoi ↗

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11Characters who always tell the truth or always lie populate this classic family of identity-deduction puzzles.IDENTIFY
The Knights and Knaves Puzzle
Knights and knaves puzzles feature characters who always lie or always tell the truth, requiring careful deduction.
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12Checkmate ends this strategy game played with kings, queens and other pieces on a 64-square board.RECALL
Chess
Chess, played on a 64-square board, has been studied and played competitively for over a thousand years.
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13Twisting rows and columns restores six solid-colour faces on this Hungarian inventor's famous 3 × 3 × 3 puzzle.RECALL
The Rubik's Cube
The Rubik's Cube has about 43 quintillion reachable configurations. In the usual solved state, each of its six faces has a single colour.
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