In the 1870s, the following so-called "15"-puzzle "drove the entire [western] world crazy" [Archer ..]. The task is to push the squares to the empty place and eventually order them in increasing order, meaning that the first row shows, 1,2,3,4 the second row shows 5,6,7,8, and so on, until the last row shows 13,14,15 and the empty space. Just try it!
By the way: The yellow squares are already where they belong.