posted by tia .
if you take apart 5x5x5 cube and build a pyramid with the same cubes, with each layer of the pyramid being a square and the top ending as a 1x1x1. How many tiers can you make?
I assume that the larger cube is made up of 125 (5*5*5) 1x1x1 cubes. You can start at the top with 1 cube, 4 (2^2) cubes, 9 (3^2) cubes... and so on, until you have used all 125. You may have some leftover cubes.