Reference : Metric Prefixes

Prefix in metric system is intended to shorten the writing of a metric unit. In telecommunication, units are often written with prefixes. For example, frequency is given in kHz (kilo Hertz), MHz (mega Hertz), or GHz (giga Hertz) and bit rate in kbps (kilo bit per second) or Mbps (mega bit per second).  

The following table serves as a reminder to the prefixes in metric system.

Prefix Factor Symbol
yotta 1024 Y
zetta 1021 Z
exa 1018 E
peta 1015 P
tera 1012 T
giga 109 G
mega 106 M
kilo 103 k
hecto 102 h
deka 101 da
deci 10-1 d
centi 10-2 c
milli 10-3 m
micro 10-6 μ
nano 10-9 n
pico 10-12 p
femto 10-15 f
atto 10-18 a
zepto 10-21 z
yocto 10-24 y

A prefix gives multiplication or subdivision of a certain unit with the prefix factor. For example, 1 Mbps = 1 x 106 bps or 1 million bits per second. 1 nm (nanometer) equals 1 x 10-9 meter or 1 billionth meter.