It depends on what the "90" is. You forgot to include the unit with that number,
so there's no way to calculate the answer to the question.
13 ft * 90 ft = 13*90 sq feet = 1170 sq feet.
There's about 969 square feet in 90 square meters
90 * 330 = 29700 sq ft
90 x 7 = 630 sq ft
1620 sq ft
2640 ft x 90 ft = 237,600 sq ft 237,600 sq / 43,560 sq per acre = 5.45455 acres
1 cubic yard will cover ~90 sq feet
To get square footage you multiply the width by the length. In this case 90 times 50 equals 4500 sq. feet
It is: 42 feet by 90 feet = 42*90 = 3780 square feet
Assuming the circle has a diameter of 90 feet, its area is pi*(90/2)2 = 6362 sq ft approx.
If that's 12 x 90 feet, it's 1080 square feet. If that's 12 x 90 inches, it's 7.5 square feet.
1 acre is 220 feet wide and 198 long. multiplied by 90 = 19,800 X 17,820 feet Sadly incorrect. If you multiply each dimension by 90 you end up with 90x too many acres... If 1 acre is 220x198, the area is 43,560 sq. feet. 90 acres is 3,920,400 sq. feet, which is a square about 1,980 feet in length and width.