One centimeter is equal to 10 millimeters. It is also equal to 0.1 decimeter and 0.01 meter. One kilometer contains 100,000 centimeters. Millimeters, decimeters, centimeters, meters and kilometers are all units of length in the metric system.
The metric system is based on units of 10, with standard prefixes attached to the basic unit of measurement. In this case, the basic unit is the meter. The prefix milli- means one thousandth, centi- means one hundredth, deci- means one tenth and kilo- means one thousand. One major advantage of the metric system is that conversions within the system often require little more than moving a decimal point.