The answer depends on the units of measurement used for the numbers in the question: feet, metres, centimetres, miles, etc.
90
Assuming 9x9 is also in feet, then answer is 81 square feet.
141.75
If it is nine feet by nine feet, then it is 81 square feet.
16 if there is no wastage or cutting.
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.
To turn a 9x9 square into an octagon you can cut corners off the square. It will not be a regular octagon though.
Each tile covers 81 square inches. You have 1,296 square inches to cover. It will take 16 tiles to cover that area.
81
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.
81 (9x9) & 9 (3x3)
Well, you've essentially got 27 square feet (9' x 9' x 0.333') which is equal to 1 cubic yard.