21 US dry barrels in US gallons

Conversion formula
How to convert 21 US dry barrels to US gallons?

We know (by definition) that: $1\mathrm{drybarrel}\approx 30.5454545454545\mathrm{usgallon}$

We can set up a proportion to solve for the number of US gallons.

Now, we cross multiply to solve for our unknown $x$:

Conclusion: 21 ⁢ drybarrel ≈ 641.4545454545445 ⁢ usgallon

Conversion in the opposite direction

The inverse of the conversion factor is that 1 US gallon is equal to 0.00155895691609977 times 21 US dry barrels.

It can also be expressed as: 21 US dry barrels is equal to $\frac{1}{\mathrm{0.00155895691609977}}$ US gallons.

Approximation

An approximate numerical result would be: twenty-one US dry barrels is about six hundred and forty-one point four five US gallons, or alternatively, a US gallon is about zero times twenty-one US dry barrels.