I don't know if I am correct or not, but I believe that you have to multiply the perimeter of your base and then multiply that by the height of your cube.
So in this case, you would do 4 x 4, since a cube is basically 6 squares, and a square has 4 sides.
4 x 4 = 16
Then the height is 4 as well.
16 x 4 = 64² (I believe you have to square the total as well, so don't forget that.)
If I am incorrect, please let me know. But I really do hope this helped. :)
