40 millimeters in kilometers

Conversion formula
How to convert 40 millimeters to kilometers?

We know (by definition) that: $1\mathrm{mm}=1e-06\mathrm{km}$

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

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

Conclusion: 40 ⁢ mm = 3.9999999999999996e-05 ⁢ km

Conversion in the opposite direction

The inverse of the conversion factor is that 1 kilometer is equal to 25000 times 40 millimeters.

It can also be expressed as: 40 millimeters is equal to $\frac{1}{\mathrm{25000}}$ kilometers.

Approximation

An approximate numerical result would be: forty millimeters is about zero kilometers, or alternatively, a kilometer is about twenty-five thousand times forty millimeters.