The math is pretty straight forward 18 times 18 is 324 square feet
if you are interested in square yards for flooring it would be 18X18=324 then divide by 9 for sq Yard's= 324/9=36 sq yards
in carpet or vinyl a 12'X27 would be enough square feet but would need a bit more for pattern matching and trim waste..
If you are figuring for flooring please remember that 324 is the NET flooring area. some waste is always a part of the project.
216 square feet (18 x 12 = 216).
288 square feet.
400
For area measurements, you multiply the length by the width. Here the calculation gives you an answer of 216 square feet.
6
400 square feet.
525 square feet.
120 square feet.
252 square feet.
324 square feet.
140 square feet.
352 square feet.
130 square feet.
770 square feet.
240 square feet