ref: d60192531e3ee6b492151f6aa8edd481ebddcdf7
dir: /html/sixteen.html/
Sixteen <p> Slide the grid squares around so that the numbers end up in consecutive order from the top left corner. <p> Click on the arrows at the edges of the grid to move a row or column left, right, up or down. The square that falls off the end of the row comes back on the other end.