Metric Prefixes

To help the SI units apply to a wide range of phenomena, the 19th General Conference on Weights and Measures in 1991 extended the list of metric prefixes so that it reaches from yotta- at 1024 (one septillion) to yocto- at 10-24 (one septillionth). Here are the metric prefixes, with their numerical equivalents stated in the American system for naming large numbers:

 

SI Unit Prefixes
Prefix	Symbol	Meaning	Base Unit Multiplied by	Factor
yotta-	Y	septillion	1,000,000,000,000,000,000,000,000	1024
zetta-	Z	sextillion	1,000,000,000,000,000,000,000	1021
exa-	E	quintillion	1,000,000,000,000,000,000	1018
peta-	p	quadrillion	1,000,000,000,000,000	1015
tera-	T	trillion	1,000,000,000,000	1012
giga-	g	billion	1,000,000,000	109
mega-	M	million	1,000,000	106
kilo-	k	thousand	1,000	103
hecto-	h	hundred	100	102
deca-	da	ten	10	101
Base units, no prefix - Ex.- meter, liter, gram				100
deci-	d	tenth	0.1	10-1
centi-	c	hundredth	0.01	10-2
milli-	m	thousandth	0.001	10-3
micro-	u	millionth	0.000001	10-6
nano-	n	billionth	0.000000001	10-9
pico-	p	trillionth	0.000000000001	10-12
femto-	f	quadrillionth	0.000000000000001	10-15
atto-	a	quintillionth	0.000000000000000001	10-18
zepto-	z	sextillionth	0.000000000000000000001	10-21
yocto-	y	septillionth	0.000000000000000000000001	10-24

What's it all mean? A kilometer is a thousand meters, a kiloliter is a thousand liters, a kilogram is a thousand grams; a centimeter is a hundredth of a meter, a centiliter is a hundredth of a liter, a centigram is a hundredth of a gram. The prefixes can be applied to any kind of SI unit. Only temperature degrees (Celsius or Kelvin in SI) seem to be exempt. Also, there is no accepted metric time system in use.