Giga-

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For other meanings, see Giga (disambiguation)
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Giga- (symbol: G) is a prefix in the SI system of units denoting 109, or 1,000,000,000 (1 thousand million). The Oxford English Dictionary reports the earliest written use of giga- in this sense to be in the Reports of the IUPAC 14th Conference in 1947: "The following prefixes to abbreviations for the names of units should be used: G giga- 109×". Giga- comes from the Greek γίγας, meaning 'giant'.

When referring to computing information units, such as gigabit or gigabyte, giga- can sometimes mean 1,073,741,824 (230), (Though such use is incorrect) and is better used only to denote strictly 1,000,000,000 (109). Any ambiguity is best resolved from context. The binary prefix gibi- has been standardized for 230, while reserving giga- exclusively for 109, to resolve this ambiguity, but has yet to achieve widespread usage. See binary prefix.

Contents

Pronunciation

In English the initial g of giga is properly pronounced with a hard g (as in giggle) but is sometimes pronounced with a soft g (as in giant). According to the American writer Self, in the 1920s a German committee member of the International Electrotechnical Commission proposed giga- as a prefix for 109, drawing on a verse by the humorous poet Christian Morgenstern that appeared in the third (1908) edition of Galgenlieder (Gallows Songs). This suggests a hard German g was originally intended as the pronunciation. Self was unable to ascertain at what point the soft g pronunciation came into occasional use, but as of 1995 current practice had returned to hard g.[1] A prominent example of the soft G pronunciation is found in the 1985 movie Back to the Future, where gigawatts was pronounced as jigawatts.

In the United States, it is well documented that the National Bureau of Standards issued pronunciation guides for the metric prefixes in the 1960s and again as late as the 1980s, giving the 'g' in "giga" a soft "j" sound, thus formalizing the pronunciation as "jiga"[2] within the United States.

Common usage

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
  1. The metric system was introduced in 1795 with six prefixes. The other dates relate to recognition by a resolution of the CGPM.
  2. The 1948 recognition of the micron by the CGPM was abrogated in 1967.

See also

Notes and references

  1. ^ Kevin Self. (April 1995). "Technically speaking". Spectrum.
  2. ^ NBS Special Publication 304 & 304A, revised August, 1981, "A Brief History of Measurement Systems"

External links

Retrieved from "http://en.wikipedia.org/wiki/Giga-"

This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.

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