In the metric system, each of the common kinds of measure — length, weight, capacity — has one basic unit of measure.  To measure smaller amounts, divide the basic unit into parts of ten, a hundred, or a thousand, and so on.  To measure larger amounts, multiply the basic unit by ten, a hundred, or a thousand, and so on.  

 Length:

1 kilometer (km) = 1000 meters (m)
1 centimeter (cm) = .01 meter (m)
1 millimeter (mm) = .001 meter (m)

Weight:

1 kilogram (kg) = 1000 grams (g)
1 milligram (mg) = .001 gram (g)

Capacity:

1 milliliter = .001 liter (l)