640 miles in kilometers

Conversion formula
How to convert 640 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: 640 ⁢ mile = 1029.98016 ⁢ km

Conversion in the opposite direction

The inverse of the conversion factor is that 1 kilometer is equal to 0.000970892487870834 times 640 miles.

It can also be expressed as: 640 miles is equal to $\frac{1}{\mathrm{0.000970892487870834}}$ kilometers.

Approximation

An approximate numerical result would be: six hundred and forty miles is about one thousand and twenty-nine point nine eight kilometers, or alternatively, a kilometer is about zero times six hundred and forty miles.