2.25 square feet
220
It is not clear what is meant by an "18x18 square feet" tile. 18ft * 18 ft = 324 square feet, so that one tile will be more than enough. An 18 inch by 18 inch tile cannot be a 18x18 square feet tile.
You'll need 200 18-inch tiles.
266.666666666 so rounding up 267 tiles.
22.2 tiles so buy 23 tiles.
exactly 8
18" x 18" = 1.5' x 1.5' = 2.25 square feet90/2.25 = 40 tiles.
The conversion factor to change an area in square inches to square feet is 1 square inch is equal to 0.0069427252080 square foot. So, 100 square inches is equal to 0.69427 square feet using this conversion factor.
144 square inches is one square foot
23.41 sq m
18 inches is equal to 1.5 feet.Therefore the area is 1.52 = 2.25 square feet.