Hecto-
Hecto (symbol: h) is a decimal unit prefix in the metric system denoting a factor of one hundred. It was adopted as a multiplier in 1795, and comes from the Greek ἑκατόν ékatón, meaning "hundred". In 19th century English it was sometimes spelled hecato, in line with a puristic opinion by Thomas Young.[1][2] Its unit symbol as an SI prefix in the International System of Units (SI) is the lower case letter h.
Look up hecto- in Wiktionary, the free dictionary. |
It is rarely used except in certain specific applications:
- hectopascal (hPa), in meteorology, for atmospheric pressure, the modern equivalent of the traditional millibar.
- hectolitre (hl or hL), in agriculture, for liquids (notably wine and milk) and bulk commodities (e.g., grain).
- hectogram (hg), in agronomy, for quantities of animal feed (hectogram/animal) and for measures of agricultural productivity (hectogram/hectare); also used in Italy abbreviated as etto, and in Canada, New Zealand and Sweden simply as 100 g, for retail sale of cold cuts and meat.
- hectometre (hm), in radio astronomy, occasionally used to indicate a radio band by wavelength
- hectare (ha, or 100 ares), in surveying, as a measure of land area equal to one square hectometre, 1 (hm)2 = 10,000 m2
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 | |
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See also
References
- Brewster, David (1832). The Edinburgh Encyclopaedia. 12 (1st American ed.). Joseph and Edward Parker. Retrieved 2015-10-09.
- Dingler, Johann Gottfried (1823). Polytechnisches Journal (in German). 11. Stuttgart, Germany: J.W. Gotta'schen Buchhandlung. Retrieved 2015-10-09.
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