Description:
This puzzle goes by the name "15-puzzle" when played with four rows and four columns. You can pick from 27 different varieties based on the number of rows and columns.

Objective:
Slide the numbers around until they are in numerical order from least to greatest, left to right and top to bottom.
The white space is the open space that the numbered squares are moved to. To move a number, click on it. Only numbers that are immediately to the left, right, above or below the empty space can be moved. The open space should end up in the lower right hand corner when the puzzle has been solved.