How many 4 inch x 4 inch ceramic tiles would it take to cover a 120 square foot area?

There are 12 inches in a foot, since the tiles are 4 inches on each side. It will take 3 tiles to get a foot. Therefore it will take 9 (3*3) tiles to make a square foot.

Since you need to cover 120 square foot area, you multiple the total square foot area by 9
120 * 9
=1080.
Therefore, you need 1080 4 inch x 4 inch ceramic tiles to cover 120 square foot area.

What formula is used to get the answer of 1080?