The metric system has prefix modifiers that are multiples of 10.

• A kilogram is 1000 grams
• A hectogram is 100 grams
• A decagram is 10 grams
• A gram is the stem unit of mass
• A decigram is 1/10 gram
• A centigram is 1/100 gram
• A milligram is 1/1000 gram

As we move down the units, the next unit is one tenth as heavy. As we move upward, each unit is 10 times as heavy. One hundred milligrams, which is 1/10 gram (100/1000=1/10) are heavier than one centigram (1/100th gram).