Iran Civil Center

ISSN: 1735–2614
November 21, 2008
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International System of Units
The International System of Units (or Système International d´Unites - SI) is the current form of the metric system that has been in use since 1960.

Base Units
There are seven base units in SI:

 Unit  Symbol  Quantity
 meter  m  length
 kilogram  kg  mass
 second  s  time
 ampere  A  electric current
 kelvin  K  (thermodynamic) temperature
 candela  cd  luminous intensity
 mole  mol  amount of substance


Metric Prefixes

 Prefix      Meaning      Symbol   Multiplication Factors    
 yotta  one septillion  Y
1e24 1,000,000,000,000,000,000,000,000
 zetta  one sextillion  Z
1e21 1,000,000,000,000,000,000,000
 exa  one quintillion  E
1e18 1,000,000,000,000,000,000
 peta  one quadrillion  P
1e15 1,000,000,000,000,000
 tera  one trillion  T
1e12 1,000,000,000,000
 giga  one billion  G
1e9 1,000,000,000
 mega  one million  M
1e6 1,000,000
 kilo  one thousand  k
1e3 1,000
 hecto  one hundred  h
1e2 100
 deca / deka  ten  da
1e1 10
 deci  one tenth  d
1e-1 0.1
 centi  one hundredth  c
1e-2 0.01
 milli  one thousandth  m
1e-3 0.001
 micro  one millionth  µ
1e-6 0.000 001
 nano  one billionth  n
1e-9 0.000 000 001
 pico  one trillionth  p
1e-12 0.000 000 000 001
 femto  one quadrillionth  f
1e-15 0.000 000 000 000 001
 atto  one quintillionth  a
1e-18 0.000 000 000 000 000 001
 zepto  one sextillionth  z
1e-21 0.000 000 000 000 000 000 001
 yocto  one septillionth  y
1e-24 0.000 000 000 000 000 000 000 001