Most of the world uses the metric system. The only countries not on this system are the U.S., Myanmar, and Liberia.

The metric system is based on 10s. For example, 10 decimeters make a meter (39.37 inches).

Units smaller than a meter have Latin prefixes:

• Deci- means 10; 10 decimeters make a meter.
• Centi- means 100; 100 centimeters make a meter.
• Milli- means 1,000; 1,000 millimeters make a meter.

Units larger than a meter have Greek prefixes:

• Deka- means 10; a dekameter is 10 meters.
• Hecto- means 100; a hectometer is 100 meters.
• Kilo- means 1,000; a kilometer is 1,000 meters.

Helpful Hints

Remember: A meter is a little more than a yard. A kilometer is less than a mile. A liter is a little more than a quart.

The Metric System