The Math Of The Rubik's Cube

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Last August, 30 years after the Rubik's cube first appeared, an international team of researchers proved that no matter how scrambled a Rubik's cube got, it could be solved in no more than 20 moves.
Although the researchers used some clever tricks to avoid evaluating all 43 quintillion of the cube's possible starting positions, their proof still relied on the equivalent of 35 years' worth of number crunching on a good modern computer.
(via Look At This...)The Presurfer