most of the world (except the United States ) today. The prefixes below are commonly used to measure meters , litres , grams , and seconds . Prefix Symbol Measurement Number Scientific Notation   Yotta- Y septillion 1 ,000,000,000,000,000,000,000,000 10 24   Zetta- Z sextillion 1 ,000,000,000,000,000,000,000 10 21   Exa-