The puzzle was invented by Noyes Palmer Chapman in 1874.
Sam Loyd claimed from 1891 until his death in 1911 that he invented the puzzle.
Loyd offered a $1,000 prize for anyone who could provide a solution for achieving a particular combination reversing the 14 and 15.
This was impossible, as it required a transformation from an even to an odd combination.


The goal is to place the tiles in order.
1 2 3 4
5 6 7 8
9 10 11 12
13 14 15

You can do sliding moves that use the empty space. You cannot remove a stone from the puzzle.