posted by Arnau .
You are planning to lay square tiles on an entire 21125cm by 54925cm rectangular floor without any overlapping. If all the square tiles must be of the same size, what is the least possible number you can lay?
21125 = 5^3 13^2
54925 = 5^2 13^3
So, if the tiles are 5^2*13^2 = 4225 cm square, the floor is 5x13 = 65 tiles.
Those are some tiles: 42.25 meters on a side!