Femto-

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Femto- (symbol f) is a unit prefix in the metric system denoting a factor of 10−15 or 0.000000000000001. Adopted by the 11th General Conference on Weights and Measures, [1] it was added in 1964 to the SI. [2] It is derived from the Danish word femten, meaning "fifteen".

Examples of use:

The femtometre shares the unit symbol (fm) with the older non-SI unit fermi , to which it is equivalent. The fermi, named in honour of Enrico Fermi, is often encountered in nuclear physics.

PrefixBase 1000Base 10 Decimal English wordAdoption [nb 1]
NameSymbol Short scale Long scale
yotta Y 10008  1024 1000000000000000000000000 septillion quadrillion1991
zetta Z 10007  1021 1000000000000000000000 sextillion trilliard1991
exa E 10006  1018 1000000000000000000 quintillion trillion1975
peta P 10005  1015 1000000000000000 quadrillion billiard1975
tera T 10004  1012 1000000000000 trillion billion1960
giga G 10003  109 1000000000 billion milliard1960
mega M 10002  106 1000000 million1873
kilo k 10001  103 1000 thousand1795
hecto h 10002/3  102 100 hundred1795
deca da 10001/3  101 10 ten1795
 10000  100 1 one
deci d 1000−1/3  10−1 0.1 tenth1795
centi c 1000−2/3   10−2 0.01 hundredth1795
milli m 1000−1  10−3 0.001 thousandth1795
micro μ 1000−2  10−6 0.000001 millionth1873
nano n 1000−3  10−9 0.000000001 billionth milliardth1960
pico p 1000−4  10−12 0.000000000001 trillionth billionth1960
femto f 1000−5  10−15 0.000000000000001 quadrillionth billiardth1964
atto a 1000−6  10−18 0.000000000000000001 quintillionth trillionth1964
zepto z 1000−7  10−21 0.000000000000000000001 sextillionth trilliardth1991
yocto y 1000−8  10−24  0.000000000000000000000001 septillionth quadrillionth1991
  1. Prefixes adopted before 1960 already existed before SI. 1873 was the introduction of the CGS system.

References

  1. International Bureau of Weights and Measures (2006), The International System of Units (SI) (PDF) (8th ed.), ISBN   92-822-2213-6, archived (PDF) from the original on 2017-08-14
  2. BIPM - Resolution 8 of the 12th CGPM

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