International System of Units
Units! What are they, how do they work?
Introduction
With the notable exception of a certain North American country which shall go unnamed, virtually the entire planet has chosen to adopt a single International System of Units (Système International or SI) that may be used to add dimension to physical measurements.
This is really just a fancy way of saying that (almost) everyone uses scientific notation and kilograms, instead of silliness and pounds, to measure weight.
Some of these units are kilograms, kilometres, seconds and joules, for mass, distance, time and energy, respectively.
You may have noticed that these units are prefixed (preceded by) zero or one prefixes; in this case, kilo. An SI prefix is actually just an alias for a particular power of ten. That is to say, SI prefixes are actually a way of using scientific notation to make using these units easier.
Tables
The first table lists all prefixes which are multiples of a unit, while the second table lists all prefixes which are submultiples of a unit.
Each table provides the prefix's value in scientific notation, the prefix's name and the prefix's symbol.
Multiples
| Factor | Name | Symbol |
|---|---|---|
| \(10^{24}\) | Yotta | \(\text{Y}\) |
| \(10^{21}\) | Zetta | \(\text{Z}\) |
| \(10^{18}\) | Exa | \(\text{E}\) |
| \(10^{15}\) | Peta | \(\text{P}\) |
| \(10^{12}\) | Tera | \(\text{T}\) |
| \(10^{9}\) | Giga | \(\text{G}\) |
| \(10^{6}\) | Mega | \(\text{M}\) |
| \(10^{3}\) | Kilo | \(\text{k}\) |
| \(10^{2}\) | Hecto | \(\text{h}\) |
| \(10^{1}\) | Deka | \(\text{da}\) |
Submultiples
| Factor | Name | Symbol |
|---|---|---|
| \(10^{-1}\) | deci | \(\text{d}\) |
| \(10^{-2}\) | centi | \(\text{c}\) |
| \(10^{-3}\) | milli | \(\text{m}\) |
| \(10^{-6}\) | micro | \(\mu\) |
| \(10^{-9}\) | nano | \(\text{n}\) |
| \(10^{-12}\) | pico | \(\text{p}\) |
| \(10^{-15}\) | femto | \(\text{f}\) |
| \(10^{-18}\) | atto | \(\text{a}\) |
| \(10^{-21}\) | zepto | \(\text{z}\) |
| \(10^{-24}\) | yocto | \(\text{y}\) |
