The Metric System

This is basically scientific notation with words. For example, 1 kilometer represents 1000 meters or $10^3$ meters, or 1 milligram is 0.001 grams or $10^{-3}$ grams. Here is a table of common metric prefixes:

giga-	$10^9$	1 billion	1,000,000,000
mega-	$10^6$	1 million	1,000,000
kilo-	$10^3$	1 thousand	1,000
centi-	$10^{-2}$	1 hundredth	1/100
milli-	$10^{-3}$	1 thousandth	1/1000
micro-	$10^{-6}$	1 millionth	1/1,000,000
nano-	$10^{-9}$	1 billionth	1/1,000,000,000