In order to keep figures short and presentable, SI prefixes are often attached to units such as m (meter) or g (gram).

For example, a substance weighing 0.000 000 001 g may be described more simply as 1 ng (nanogram) or as 1000 pg (picograms).

Common prefixes of the International System of Units (SI) are:

p pico = 1 000 000 000 000th = 10-12

n nano = 1 000 000 000th = 10-9

µ micro = 1 000 000th = 10-6

m milli = 1 000th = 10-3

no prefix = 1

k kilo = 1 000 = 103

M Mega = 1 000 000 = 106

G Giga = 1 000 000 000 = 109

T Tera = 1 000 000 000 000 = 1012