Okay, here we have this:
We need to convert 31 m to centimeters, so we are going to do it considering that in a meter there are 100 centimeters:
[tex]\begin{gathered} 31m\cdot\frac{100\operatorname{cm}}{1m} \\ =310\operatorname{cm} \end{gathered}[/tex]Finally we obtain that 31m are 310 centimeters.