21 US quarts in US customary cups

Conversion formula
How to convert 21 US quarts to US customary cups?

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

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

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

Conclusion: 21 ⁢ usquart ≈ 84 ⁢ uscup

Conversion in the opposite direction

The inverse of the conversion factor is that 1 US customary cup is equal to 0.0119047619047619 times 21 US quarts.

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

Approximation

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