Nine you retard! Twelve by twelve inches is one square foot you GENIUS!
P.S. If you are not setting them straight by staright, you would want to leave about inch of plaster in between each tile so they wont break easy and can expand and shrink with the cold weather.
157 18 by 18 tiles are needed to cover 352 square feet.
5,184 2-square-inch tiles are needed.
1540
18..
647
157 18 by 18 tiles are needed to cover 352 square feet.
6' x 9' (54 square feet) = 6 square yards of tiles needed.
240 square tiles are needed
5,184 2-square-inch tiles are needed.
236 18-inch tiles.
Each tile covers 4 square feet. Which means you need 200 tiles to cover 800 square feet, plus spoilage.
1540
18..
647
968
616 3x6 inch tiles are needed to cover exactly 77 square feet.
216- 2x2