21 US gallons in US quarts

Conversion formula
How to convert 21 US gallons to US quarts?

We know (by definition) that: $1\mathrm{usgallon}\approx 4\mathrm{usquart}$

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

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

Conclusion: 21 ⁢ usgallon ≈ 84 ⁢ usquart

Conversion in the opposite direction

The inverse of the conversion factor is that 1 US quart is equal to 0.0119047619047619 times 21 US gallons.

It can also be expressed as: 21 US gallons is equal to $\frac{1}{\mathrm{0.0119047619047619}}$ US quarts.

Approximation

An approximate numerical result would be: twenty-one US gallons is about zero US quarts, or alternatively, a US quart is about zero point zero one times twenty-one US gallons.