In the SI system the units of measurement are related decimally by powers of 10.

As shown here, there are 10 millimeters in a centimeter and 10 centimeters in a decimeter. There are 10 decimeters in a meter.

In this system, measurements are expressed in a base unit.

Smaller or larger quantities are specified by prefixes. Here the base unit is meter and the prefixes are milli-, centi- and deci-.