18" x 18" = 1.5 ft x 1.5 ft = 2.25 sq ft.
Number of tiles required = 700/2.25 = 311.11... so 312 tiles are required.
That is the mathematical answer to the question. In real life, you will need to make an allowance for your skill level and the awkwardness of the shape being tiled - which will affect the proportion of offcuts that can be used.
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