40 centimeters in millimeters

Conversion formula
How to convert 40 centimeters to millimeters?

We know (by definition) that: $1\mathrm{cm}=10\mathrm{mm}$

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

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

Conclusion: 40 ⁢ cm = 400 ⁢ mm

Conversion in the opposite direction

The inverse of the conversion factor is that 1 millimeter is equal to 0.0025 times 40 centimeters.

It can also be expressed as: 40 centimeters is equal to $\frac{1}{\mathrm{0.0025}}$ millimeters.

Approximation

An approximate numerical result would be: forty centimeters is about four hundred millimeters, or alternatively, a millimeter is about zero times forty centimeters.