A 64-disc puzzle comes with a legend that finishing it ends the world
Three pegs hold a stack of discs of different sizes. Move the whole stack from one peg to another, one disc at a time, never placing a larger disc on top of a smaller one. Édouard Lucas invented this toy in 1883 and packaged it with a myth: Brahmin priests in an Indian temple are supposedly moving 64 golden discs this way, and when they finish, the world will end.
Reveal the answer
The minimum number of moves for n discs is 2^n minus 1, so for 64 discs that is over 18 quintillion moves. Moving one disc per second nonstop, the priests would need roughly 585 billion years, far longer than the universe has existed. Lucas invented the Brahmin legend himself to market the puzzle as a toy, publishing it under the pseudonym 'N. Claus de Siam,' an anagram of 'Lucas d'Amiens.'