A floor 9 feet by 12 feet, is to be tiled with 4-inch-by-6-inch tiles. How many tiles are needed to cover the floor?

Each tile is 4 x 6 / 12 x 12 = 24/144 = 1/ 6 sq ft/tile

9ft x 12 ft = 108 sq ft

108 ft^{2 }/ 1/6 ft^{2}/ tile = 648 tiles