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SI Prefixes
The following prefixes are added to many units to conveniently indicate large or small numbers.
For example weight is measured in grams but is often written as kilograms indicating that the number should be multiplied by 1000 to get the weight in grams. Similarly very small quantities of a material may be expressed in milligrams indicating thousandths of a gram. i.e. 1kg = 1000g and 1mg = 0.001g
The common prefixes are:
| Symbol | Prefix | Factor (multiplier) |
| Y | yotta- | 1024 = 1,000,000,000,000,000,000,000,000 |
| Z | zetta- | 1021 = 1,000,000,000,000,000,000,000 |
| E | exa- | 1018 = 1,000,000,000,000,000,000 |
| P | peta- | 1015 = 1,000,000,000,000,000 |
| T | tera- | 1012 = 1,000,000,000,000 |
| G | giga- | 109 = 1,000,000,000 |
| M | mega- | 106 = 1,000,000 |
| k | kilo- | 103 = 1,000 |
| h | hecto- | 102 = 100 |
| da | deca- | 101 = 10 |
| d | deci- | 10-1 = 0.1 |
| c | centi- | 10-2 = 0.01 |
| m | milli- | 10-3 = 0.001 |
| u | micro- | 10-6 = 0.000,001 |
| n | nano- | 10-9 = 0.000,000,001 |
| p | pico- | 10-12 = 0.000,000,000,001 |
| f | femto- | 10-15 = 0.000,000,000,000,001 |
| a | atto- | 10-18 = 0.000,000,000,000,000,001 |
| z | zepto- | 10-21 = 0.000,000,000,000,000,000,001 |
| y | yocto- | 10-24 = 0.000,000,000,000,000,000,000,001 |