15 Puzzle!

are one of the world’s most recognized and popular puzzles. It bridges generations. 15 Puzzle! is a sliding puzzle that consists of numbered square tiles in random order with one tile missing. The object of the puzzle is to place the tiles in order by making sliding moves that use the empty space. The puzzle was "invented" by Noyes Palmer Chapman, a postmaster in Canastota, New York, who is said to have shown friends, as early as 1874, a precursor puzzle consisting of 16 numbered blocks that were to be put together in rows of four.