Sliding Tile Puzzles

The 14-15 Puzzle

The 14-15 Puzzle (not shown) was introduced by Sam Llyod in the 1870's and in his own words he "drove the world crazy" trying to solve it.  The problem is, the puzzle can not be solved.  The 14-15 Puzzle is almost identical to the 15 Puzzle shown below.  The only difference is that the 14 and 15 tiles are reversed.  It has been shown that it is mathematically impossible to move the tiles in such a way that exactly two (and only two) tiles exchange places.

8 Puzzle

15 Puzzle

49 Puzzle