Well, darling, a 16 x 20 room would have a total of 320 square feet. It's as simple as multiplying the length (16 feet) by the width (20 feet). So, go ahead and start measuring those walls if you want to double-check my math.
16' x 16' = 256 square feet.
16*16 = 256 square feet
16*16=256 ft²
192 square feet.
156 square feet
16' x 15' = 240 square feet.
16' x 16' = 256 square feet.
256 square feet
16*16 = 256 square feet
16*16=256 ft²
192 square feet.
156 square feet
28.4 square yards.
36 feet x 16 feet = 576 square feet.
352 square feet.
160 square feet.
112 square feet.