What is the square feet of a tank that is 72x24x31?

Answer 1

The proper question for a 3 dimensional tank would be what is the Cubic Feet - in this case it is simply the dimensions multiplied together (assuming they are all in feet):

72 x 24 x 31 = 53,568 cubic feet = 400,716.5 gallons

If the dimensions are actually in inches, you must convert each to feet and then multiply:

(72/12) x (24/12) x (31/12) = 6 x 2 x (31/12) = 31 cubic feet = 231.9 gallons

Now if you truly want the square feet, then you would need to know which dimension is the height and ignore it. Let's say the "31" is the height, and the dimensions are in inches. This leaves:

(72/12) x (24/12) = 6 x 2 = 12 square feet