462 cubic inches.
231 cubic inches = 1 gallon 48x48x72= 165,888 cubic inches 165888/231=718.13 gallons
You cannot change two totally different units like that - gallons are a measure of volume - how much liquid is there? Inches are a measure of how long something is. There's no way to compare them.
Gallons are determined by cubic feet. Cubic inches can be converted into cubic feet, but three measurements are needed to find cubic inches. Two measurements result in square feet, and it's impossible to determine gallons from that.
Assuming that 10 inches refer to the the inner diameter so that radius = 5 inches, the capacity is pi*52*24 = 1885 cubic inches = 8.16 US gallons.
Two US gallons is 7,570.8cc
Square inches is an area, not a volume. You can't convert square inches to gallons. If you meant CUBIC inches, then 682 cu in is 2.95 US Liquid gallons or 2.53 US Dry Gallons.
Let's see... Let's first modify the question into: "how many gallons are in a CUBIC foot" since a "square foot" is a two-dimensional area. The easiest method I can think of is to convert gallons into liters and figure volume that way since the measurements of length and volume are easily convertable. So 1 gallon = 3.784 Liters. Since 16.387 cubic cm's = 1 cubic inch, 1000 cubic cm's = 1L = 61.023 cubic inches. So this means that there are 230.914 cubic inches in one gallon. So if 1728 cubic inches is one cubic foot, 7.483 gallons will fill one cubic foot.
Making the assumptions that these measurements are in inches, and that the fish tank is a perfect cuboid, the volume of the fish tank is 49 x 19 x 21 = 19,511 cubic inches.Rounded to two decimal places, this is equal to 70.47 gallons.
Gallons are a measurement of volume; cubic feet is a measurement of area. You cannot convert between the two.
A gallon is a measure of volume, the inch is a measure of length, the two can not be equated. However the cubic inch and the gallon can be equated, there are 231.00010000000003 cubic inches in one US Gallon.
A rectangle is a two dimensional shape which does not have any volume. However, the information given in the question refer to a rectangular prism or cuboid. Its volume is 26*36*16 cubic inches = 64.8 US gallons.
There are no inches in 19 cubic feet. Inches measure length, cubic feet measure volume. You can't convert between the two.