A kilometer is 1000 meters A hectometer is 100 meters A decameter is 10 meters A meter is the basic unit of length A decimeter is 1/10 meter A centimeter is 1/100 meter A millimeter is 1/1000 meter As we move down the units, the next unit is one tenth as long. As we move upward, each unit is 10 times as long. One hundred millimeters, which is 1/10 meter (100/1000=1/10) are larger than one centimeter (1/100th meter). Converting Metric Units. The metric system has prefix modifiers that are multiples of 10. 1  A kilometer is 1000 meters. 2  A hectometer is 100 meters. 3  A decameter is 10 meters. 4  A meter is the basic unit of length.