How to convert 21 US customary cups to dry gallons?
We know (by definition) that:
We can set up a proportion to solve for the number of dry gallons.
Now, we cross multiply to solve for our unknown :
Conversion in the opposite direction
The inverse of the conversion factor is that 1 dry gallon is equal to 0.886588332302618 times 21 US customary cups.
It can also be expressed as: 21 US customary cups is equal to dry gallons.
An approximate numerical result would be: twenty-one US customary cups is about one point one two dry gallons, or alternatively, a dry gallon is about zero point eight nine times twenty-one US customary cups.
 The precision is 15 significant digits (fourteen digits to the right of the decimal point).Results may contain small errors due to the use of floating point arithmetic.