Fifteen Puzzle

    

      The goal of the fifteen puzzle is to un-jumble its fifteen squares
      by repeatedly making moves that slide squares into the empty space.
      How quickly can you solve it?
    

    

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

    

      Shuffle
    

    

      American puzzle author and mathematician Sam Loyd is often falsely
      credited with creating the puzzle; indeed, Loyd claimed from 1891
      until his death in 1911 that he invented it.
      The puzzle was actually created around 1874 by Noyes Palmer Chapman,
      a postmaster in Canastota, New York.