90
Assuming 9x9 is also in feet, then answer is 81 square feet.
141.75
The square feet of a room that has a perimeter of 36 is 81 because look. A room is a square, so you do this. 36 divided by 4 equals 9. The formula of a square that you want to find the area of is a random side times 4. 9x9=81 square feet.
If it is nine feet by nine feet, then it is 81 square feet.
16 if there is no wastage or cutting.
To turn a 9x9 square into an octagon you can cut corners off the square. It will not be a regular octagon though.
81
Each tile covers 81 square inches. You have 1,296 square inches to cover. It will take 16 tiles to cover that area.
81 (9x9) & 9 (3x3)
A 9x9 foot slab 4 inches thick requires a minimum of 1 cubic yard. If you go to 6 inches thick you will need 1.5 cubic yards.
9x9=81