31 centimeters in millimeters

Conversion formula
How to convert 31 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: 31 ⁢ cm = 310 ⁢ mm

Conversion in the opposite direction

The inverse of the conversion factor is that 1 millimeter is equal to 0.0032258064516129 times 31 centimeters.

It can also be expressed as: 31 centimeters is equal to $\frac{1}{\mathrm{0.0032258064516129}}$ millimeters.

Approximation

An approximate numerical result would be: thirty-one centimeters is about three hundred and ten millimeters, or alternatively, a millimeter is about zero times thirty-one centimeters.