21 gal
1 gallon = 16 cups
1 cup = 0.06 gallon
21 gallons is 336 cups (16 cups per gallon).
There are 8 oz. in a cup, which in turn, would covert 336 oz. to 42 cups.
336 liters is about 88.8 US gallons.
That is 336 ounces.
7 US cups = 336 US teaspoons
5.25 qts. 1 quart = 4 cups And 1 cup = 0.25 quart. There are 32 US fluid ounces (2 pints, or 4 cups) in 1 US quart (946.4 ml). There are 40 Imperial fluid ounces (2 pints) in 1 Imperial quart (1,136 ml). Note that there is no 'cup' in the Imperial system, it is best to use pints or half pints, and not 'cups'.
21 gal 1 gallon = 4 quarts 1 quart = 0.25 gallon
1 gallon = 4 quarts to 84 gallons = 84*4 = 336 quarts. Simple!
8 billion barrels (oil) equates to 336 billion US gallons.
336/7 = 48 weeks
336/60= 5.6 hours.
336 meters = 0.208 miles