You can do one of the following to calculate this:
1) Convert inches to feet. Then multiply to get the area in square feet.
2) Multiply first, to get the area, but this time in square inches. Divide the square inches by 144 to convert to square feet.
A square 20-inch tile is 2.78 square feet.
1.78 sq feet per tile.
4.694 square feet.
3.5555 square feet.
2.25 square feet
This tile has an area of 1 ft2.
Each tile would be 2.25 square feet. That means you have a total of 1,167.75 square feet of tile.
1.78 square feet.
4,800 6-inch square tiles.
There are 144 18 square inch tiles in an area of 18 square feet.
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.
1.78 square feet.