An easy way to convert centimeters to millimeters is to use the formula mm = cm/0.10000. Both are metric units of measurement, and a centimeter is one-hundredth of a meter, or 1/100, and a millimeter is one-thousandth of a meter, or 1/1000.
Converting centimeters or millimeters to inches requires conversion out of metric units of measurement. One centimeter is equal to 0.39370 inches, and one millimeter is equal to 0.0393701. Converting meters to inches only requires the movement of the decimal point two places, and thus a meter is 39.3701 inches.
Inches and feet are part of what is known as the imperial system. The majority of countries around the globe use the metric system, which includes centimeters and millimeters, and they have for some time. The United States, however, uses the imperial system in most instances. The metric system was first introduced by the country of France in 1799, and since has been an internationally agreed upon unit of measurement. While the metric system has official sanctions in the United States, the United States remains the only major industrialized nation not to fully adopt the system. Other countries that do not use the metric system and favor the imperial system include Liberia and Burma.