Short answer: Multiply meters by (100 for centimeters) or multiply by (1000 for millimeters).
The metric system makes it easy to convert between different units because the whole system is base ten. Each new unit of measure is ten times greater or ten times smaller than the last. As long you remember the names, it becomes easy to convert between them.
decimeter 0.1 (rarely used)
We're given 32.7 meters (m) and we'd like to know how many centimeters (cm) that is. Let's start with what we know:
1 m = 100 cm
We can set up a proportion to solve for the number of centimeters. We are given 3 pieces of information, and asked to find a 4th:
Note: Make sure to be consistent with your units (in this case, meters in the numerator and centimeters in the denominator). Otherwise, you will end up with the incorrect answer!
Now, cross multiply to solve for our unknown
We're given 0.062 meters (m) and we'd like to know how many millimeters (mm) that is. Let's start with what we know:
1 m = 1,000 mm. Set up your proportion:
Cross multiply to solve for our unknown
After completing a bunch of these problems, you may notice that to convert from meters to centimeters to millimeters, you simply multiply the meters by 100 or 1000 respectively.
Easy to read and understand here: https://www.mathsisfun.com/measure/metric-length.html