640 kilometers in miles

Conversion formula
How to convert 640 kilometers to miles?

We know (by definition) that: $1\mathrm{km}\approx 0.62137119\mathrm{mile}$

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

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

Conclusion: 640 ⁢ km ≈ 397.6775616 ⁢ mile

Conversion in the opposite direction

The inverse of the conversion factor is that 1 mile is equal to 0.0025146 times 640 kilometers.

It can also be expressed as: 640 kilometers is equal to $\frac{1}{\mathrm{0.0025146}}$ miles.

Approximation

An approximate numerical result would be: six hundred and forty kilometers is about three hundred and ninety-seven point six eight miles, or alternatively, a mile is about zero times six hundred and forty kilometers.