Definition: | unit prefix used together with a SI unit to form decimal multiples or submultiples of this unit
NOTE 1 – The list of approved SI prefixes is given in the following table:
Multiples
|
Submultiples
|
Factor
|
Prefix
|
Factor
|
Prefix
|
Name
|
Symbol
|
Name
|
Symbol
|
101
|
deca
|
da
|
10–1
|
deci
|
d
|
102
|
hecto
|
h
|
10–2
|
centi
|
c
|
103
|
kilo
|
k
|
10–3
|
milli
|
m
|
106
|
mega
|
M
|
10–6
|
micro
|
μ
|
109
|
giga
|
G
|
10–9
|
nano
|
n
|
1012
|
tera
|
T
|
10–12
|
pico
|
p
|
1015
|
peta
|
P
|
10–15
|
femto
|
f
|
1018
|
exa
|
E
|
10–18
|
atto
|
a
|
1021
|
zetta
|
Z
|
10–21
|
zepto
|
z
|
1024
|
yotta
|
Y
|
10–24
|
yocto
|
y
|
NOTE 2 – When the prefixes are used, the prefix name and the unit name are combined to form a single word, and similarly the prefix symbol and the unit symbol are written without any space to form a single symbol, which may itself be raised to any power. For example, we may write: kilometre, km; microvolt, μV; femtosecond, fs;
50 V/cm = 50 V (10–2 m)–1 = 5000 V/m. See the SI Brochure for more information.
NOTE 3 – As an exception, multiples and submultiples of the kilogram are written by combining a prefix with the gram, such we write: milligram, mg, not microkilogram, µkg.
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