The answer depends on the size of the area to be covered. And since you have not bothered to provide that information, I cannot provide a more useful answer.
One side of a square is 10 inches long. How many one square inch tiles are needed to cover its area?
125
To cover an area of 1 square foot with 1/2 inch of water, you would need 0.623 gallons of water.
The perimeter of a square is 100 inches. How many square tiles 1 inch on each edge are needed to cover its area?
You will need 44 six inch tiles to cover 11 square feet.
5,184 2-square-inch tiles are needed.
288 6-inch tiles are needed.
236 18-inch tiles.
144
647
968
54