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 hekatón, 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.
The prefix is rarely used in general, but has 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
- In surveying, a square hectometre is called a hectare (ha, or 100 ares = 1 hm2 = 10,000 m2).
| Prefix | Base 10 | Decimal | Adoption [nb 1] | |
|---|---|---|---|---|
| Name | Symbol | |||
| quetta | Q | 1030 | 1000000000000000000000000000000 | 2022[3] |
| ronna | R | 1027 | 1000000000000000000000000000 | 2022 |
| yotta | Y | 1024 | 1000000000000000000000000 | 1991 |
| zetta | Z | 1021 | 1000000000000000000000 | 1991 |
| exa | E | 1018 | 1000000000000000000 | 1975 |
| peta | P | 1015 | 1000000000000000 | 1975 |
| tera | T | 1012 | 1000000000000 | 1960 |
| giga | G | 109 | 1000000000 | 1960 |
| mega | M | 106 | 1000000 | 1873 |
| kilo | k | 103 | 1000 | 1795 |
| hecto | h | 102 | 100 | 1795 |
| deca | da | 101 | 10 | 1795 |
| 100 | 1 | — | ||
| deci | d | 10−1 | 0.1 | 1795 |
| centi | c | 10−2 | 0.01 | 1795 |
| milli | m | 10−3 | 0.001 | 1795 |
| micro | μ | 10−6 | 0.000001 | 1873 |
| nano | n | 10−9 | 0.000000001 | 1960 |
| pico | p | 10−12 | 0.000000000001 | 1960 |
| femto | f | 10−15 | 0.000000000000001 | 1964 |
| atto | a | 10−18 | 0.000000000000000001 | 1964 |
| zepto | z | 10−21 | 0.000000000000000000001 | 1991 |
| yocto | y | 10−24 | 0.000000000000000000000001 | 1991 |
| ronto | r | 10−27 | 0.000000000000000000000000001 | 2022 |
| quecto | q | 10−30 | 0.000000000000000000000000000001 | 2022 |
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See also
References
- Brewster, David (1832). The Edinburgh Encyclopaedia. Vol. 12 (1st American ed.). Joseph and Edward Parker. Retrieved 2015-10-09.
- Dingler, Johann Gottfried (1823). Polytechnisches Journal (in German). Vol. 11. Stuttgart, Germany: J.W. Gotta'schen Buchhandlung. Retrieved 2015-10-09.
- "On the extension of the range of SI prefixes". 18 November 2022. Retrieved 5 February 2023.
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