Zetta-

Zetta is a decimal unit prefix in the metric system denoting a factor of 1021 or 1000000000000000000000. The prefix was added as an SI prefix to the International System of Units (SI) in 1991 and has the symbol Z.

The names zepto and zetta are implying the Latin numeral septem, meaning "seven", with the letter 'z' substituting the letter 's' to avoid the duplicate use of that letter as a symbol (i.e. SI unit for seconds). Therefore zetta was used to denote the seventh power of 1000.[1]

A prefix of the same value, hepta, was informally introduced a few years before the promulgation of zetta, but never received official sanction and is obsolete now. It was formed from the Greek ἑπτά (hepta), also meaning "seven" and already in use as a numerical prefix in this sense (e.g. heptametric). Zeta (ζήτα), although the 6th letter of the modern and classical Greek alphabet, denotes a value of seven (7) when used as a numeral.

Examples:

SI prefixes
Prefix Base 10 Decimal English word Adoption[nb 1]
Name Symbol Short scale Long scale
yotta- Y-  1024 1000000000000000000000000  septillion  quadrillion 1991
zetta- Z-  1021 1000000000000000000000  sextillion  trilliard 1991
exa- E-  1018 1000000000000000000  quintillion  trillion 1975
peta- P-  1015 1000000000000000  quadrillion  billiard 1975
tera- T-  1012 1000000000000  trillion  billion 1960
giga- G-  109 1000000000  billion  milliard 1960
mega- M-  106 1000000  million 1873
kilo- k-  103 1000  thousand 1795
hecto- h-  102 100  hundred 1795
deca- da-  101 10  ten 1795
 100 1  one –
deci- d-  10−1 0.1  tenth 1795
centi- c-  10−2 0.01  hundredth 1795
milli- m-  10−3 0.001  thousandth 1795
micro- μ-  10−6 0.000001  millionth 1873
nano- n-  10−9 0.000000001  billionth  milliardth 1960
pico- p-  10−12 0.000000000001  trillionth  billionth 1960
femto- f-  10−15 0.000000000000001  quadrillionth  billiardth 1964
atto- a-  10−18 0.000000000000000001  quintillionth  trillionth 1964
zepto- z-  10−21 0.000000000000000000001  sextillionth  trilliardth 1991
yocto- y-  10−24  0.000000000000000000000001  septillionth  quadrillionth 1991
  1. Prefixes adopted before 1960 already existed before SI. The introduction of the CGS system was in 1873.

See also

Footnotes
  1. "Resolution 4 of the 19th CGPM (Conférence Générale des Poids et Mesures)". BIPM (Bureau International des Poids et Mesures). Retrieved 2009-05-16. Les noms zepto et zetta évoquent le chiffre sept (septième puissance de 103) et la lettre « z » remplace la lettre « s » pour éviter le double emploi de la lettre « s » comme symbole.
  2. Williams, David R. (December 16, 2016), Earth Fact Sheet, NASA Goddard Space Flight Center, retrieved 2018-01-21.
  3. Qadri, Syed; Erra, Ketsia (2001). Elert, Glenn (ed.). "Volume of earth's oceans". The Physics Factbook. Retrieved 2019-07-28.
  4. http://physics.nist.gov/cgi-bin/cuu/Value?na
  5. Richard Wray (2009-05-18). "Internet data heads for 500bn gigabytes". The Guardian.
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