15 Puzzle

The 15 Puzzle is a square tablet containing 15 smaller square tiles labeled with the integers 1 to 15, set so that only one square may be moved at a time into the only available empty square by a move up or down or left or right (but never diagonally). The goal of the puzzle is to take a puzzle in an unsorted initial state, such as

7	8		1
2	3	4	5
6	9	10	11
12	13	14	15

and set each tile in its proper order.

1	2	3	4
5	6	7	8
9	10	11	12
13	14	15

The puzzle was invented by Noyes Chapman, who also created a famously unsolvable version with 14 and 15 switched. His original idea was to construct a puzzle with 16 tiles that would be moved to form a magic square with 34 as its magic constant. The 15 Puzzle was initially made of wood; today they are almost always made of plastic. Darling calls it “the Rubik’s cube of its day.”

Title	15 Puzzle
Canonical name	15Puzzle
Date of creation	2013-03-22 16:46:21
Last modified on	2013-03-22 16:46:21
Owner	PrimeFan (13766)
Last modified by	PrimeFan (13766)
Numerical id	5
Author	PrimeFan (13766)
Entry type	Definition
Classification	msc 91A24
Classification	msc 00A08
Synonym	Fifteen Puzzle
Synonym	Game of Fifteen