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Yocto-
yocto- (symbol y ) is an SI prefix in the SI system of units denoting a factor of 10−24 or 0.000000000000000000000001.
Adopted in 1991, it comes from the Greek οκτώ, meaning eight , because it is equal to 1/10008 . As of 2007 , yocto- is the smallest SI prefix to be confirmed.
It can be used for measuring a subatomic particle 's mass , for example:
SI prefixes
1000m
10n
Prefix
Symbol
Since[1]
Short scale Long scale Decimal
10008
1024
yotta- Y
1991
Septillion Quadrillion 1 000 000 000 000 000 000 000 000
10007
1021
zetta- Z
1991
Sextillion Trilliard 1 000 000 000 000 000 000 000
10006
1018
exa- E
1975
Quintillion Trillion 1 000 000 000 000 000 000
10005
1015
peta- P
1975
Quadrillion Billiard 1 000 000 000 000 000
10004
1012
tera- T
1960
Trillion Billion 1 000 000 000 000
10003
109
giga- G
1960
Billion Milliard 1 000 000 000
10002
106
mega- M
1960
Million 1 000 000
10001
103
kilo- k
1795
Thousand 1 000
10002/3
102
hecto- h
1795
Hundred 100
10001/3
101
deca- da
1795
Ten 10
10000
100
(none) (none) NA
One 1
1000−1/3
10−1
deci- d
1795
Tenth
0.1
1000−2/3
10−2
centi- c
1795
Hundredth
0.01
1000−1
10−3
milli- m
1795
Thousandth
0.001
1000−2
10−6
micro- µ
1960[2]
Millionth
0.000 001
1000−3
10−9
nano- n
1960
Billionth
Milliardth
0.000 000 001
1000−4
10−12
pico- p
1960
Trillionth
Billionth
0.000 000 000 001
1000−5
10−15
femto- f
1964
Quadrillionth
Billiardth
0.000 000 000 000 001
1000−6
10−18
atto- a
1964
Quintillionth
Trillionth
0.000 000 000 000 000 001
1000−7
10−21
zepto- z
1991
Sextillionth
Trilliardth
0.000 000 000 000 000 000 001
1000−8
10−24
yocto- y
1991
Septillionth
Quadrillionth
0.000 000 000 000 000 000 000 001
The metric system was introduced in 1795 with six prefixes. The other dates relate to recognition by a resolution of the CGPM .
The 1948 recognition of the micron by the CGPM was abrogated in 1967.
See also
