21 miles in kilometers

Conversion formula
How to convert 21 miles to kilometers?

We know (by definition) that: $1\mathrm{mile}=1.609344\mathrm{km}$

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

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

Conclusion: 21 ⁢ mile = 33.796224 ⁢ km

Conversion in the opposite direction

The inverse of the conversion factor is that 1 kilometer is equal to 0.029589104392254 times 21 miles.

It can also be expressed as: 21 miles is equal to $\frac{1}{\mathrm{0.029589104392254}}$ kilometers.

Approximation

An approximate numerical result would be: twenty-one miles is about thirty-three point seven nine kilometers, or alternatively, a kilometer is about zero point zero three times twenty-one miles.