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Hecto-
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Look up <i>hecto-</i> in Wiktionary, the free dictionary. <p><i>Hecto</i> (symbol: h) is a <a href="/facts/Decimal_prefix/Y2MzkaeL">decimal</a> <a href="/facts/Unit_prefix/CTotM82r">unit prefix</a> in the <a href="/facts/Metric_system/to24H0YK">metric system</a> denoting a factor of one hundred. It was adopted as a multiplier in 1795, and comes from the <a href="/facts/Greek_language/pzDd6eIz">Greek</a> ἑκατόν <i>hekatón</i>, meaning "hundred". In 19th century English it was sometimes spelled "hecato", in line with a <a href="/facts/Linguistic_purism/zjL5N8PF">puristic</a> opinion by <a href="/facts/Thomas_Young_(scientist)/X4RtR47L">Thomas Young</a>. Its unit symbol as an <a href="/facts/SI_prefix/Y2MzkaeL">SI prefix</a> in the <a href="/facts/International_System_of_Units/S7YLglNz">International System of Units</a> (SI) is the lower case letter h. </p><p>The prefix is rarely used in general, but has certain specific applications: </p> <ul><li><a href="/facts/Hectopascal/Am1To2Qm">hectopascal</a> (hPa), in <a href="/facts/Meteorology/xblFr28q">meteorology</a>, for <a href="/facts/Atmospheric_pressure/wJLMSaVG">atmospheric pressure</a>, the modern equivalent of the traditional <a href="/facts/Millibar/wwFWTTkT">millibar</a>.</li> <li><a href="/facts/Hectolitre/QKwbQz8I">hectolitre</a> (hl or hL), in <a href="/facts/Agriculture/TGztqzJs">agriculture</a>, for liquids (notably <a href="/facts/Milk/wDJBUHvy">milk</a> and <a href="/facts/Alcoholic_beverages/HSHVWBtX">alcoholic beverages</a>) and bulk commodities (e.g., grain).</li> <li><a href="/facts/Kilogram/lU2zbPk8">hectogram</a> (hg), in <a href="/facts/Agronomy/8pvE8bmm">agronomy</a>, for quantities of animal feed (hectogram/animal) and for measures of agricultural productivity (hectogram/hectare); also used in Italy abbreviated as <i>etto</i>, and in Canada, New Zealand and Sweden simply as 100 g, for retail sale of <a href="/facts/Cold_cut/rWRL7sRe">cold cuts</a> and meat.</li> <li><a href="/facts/Hectometre/y4vg9uCK">hectometre</a> (hm), in <a href="/facts/Radio_astronomy/TdjF4LgL">radio astronomy</a>, occasionally used to indicate a <a href="/facts/Radio_frequency/aWku7h4R">radio</a> <a href="/facts/Band_(radio)/AP2frA1C">band</a> by <a href="/facts/Wavelength/kcJU0ymz">wavelength</a></li> <li>In <a href="/facts/Surveying/qchGcnRC">surveying</a>, a square hectometre is called a <a href="/facts/Hectare/DPz2HDGr">hectare</a> (ha, or 100 <i><a href="/facts/Hectare/DPz2HDGr">ares</a></i> = 1 hm2 = 10,000 m2).</li></ul> <a href="/facts/Metric_prefix/Y2MzkaeL">SI prefixes</a><ul><li>v</li><li>t</li><li>e</li></ul><table><tbody><tr><th colspan="2">Prefix</th><th rowspan="2">Base 10</th><th rowspan="2"><a href="/facts/Decimal/7omfVNIM">Decimal</a></th><th rowspan="2">Adoption</th></tr><tr><th>Name</th><th>Symbol</th></tr><tr><td>quetta</td><td>Q</td><td><a href="/facts/Orders_of_magnitude_(numbers)/uu2o1hk2">1030</a></td><td>1000000000000000000000000000000</td><td rowspan="2">2022</td></tr><tr><td>ronna</td><td>R</td><td><a href="/facts/Orders_of_magnitude_(numbers)/uu2o1hk2">1027</a></td><td>1000000000000000000000000000</td></tr><tr><td>yotta</td><td>Y</td><td><a href="/facts/Orders_of_magnitude_(numbers)/uu2o1hk2">1024</a></td><td>1000000000000000000000000</td><td rowspan="2">1991</td></tr><tr><td>zetta</td><td>Z</td><td><a href="/facts/Orders_of_magnitude_(numbers)/uu2o1hk2">1021</a></td><td>1000000000000000000000</td></tr><tr><td>exa</td><td>E</td><td><a href="/facts/Orders_of_magnitude_(numbers)/uu2o1hk2">1018</a></td><td>1000000000000000000</td><td rowspan="2">1975</td></tr><tr><td>peta</td><td>P</td><td><a href="/facts/Orders_of_magnitude_(numbers)/uu2o1hk2">1015</a></td><td>1000000000000000</td></tr><tr><td>tera</td><td>T</td><td><a href="/facts/Orders_of_magnitude_(numbers)/uu2o1hk2">1012</a></td><td>1000000000000</td><td rowspan="2">1960</td></tr><tr><td><a href="/facts/Giga-/vdrYKueB">giga</a></td><td>G</td><td><a href="/facts/1%2c000%2c000%2c000/Ij1fl5Q7">109</a></td><td>1000000000</td></tr><tr><td><a href="/facts/Mega-/rk32jTkD">mega</a></td><td>M</td><td><a href="/facts/1%2c000%2c000/RMGVIm1j">106</a></td><td>1000000</td><td>1873</td></tr><tr><td><a href="/facts/Kilo-/akxTdXyp">kilo</a></td><td>k</td><td><a href="/facts/1000_(number)/b3LRnMBK">103</a></td><td>1000</td><td rowspan="3">1795</td></tr><tr><td>hecto</td><td>h</td><td><a href="/facts/100/G6ynN9mT">102</a></td><td>100</td></tr><tr><td><a href="/facts/Deca-/IkCqeowc">deca</a></td><td>da</td><td><a href="/facts/10/pqN3l0vm">101</a></td><td>10</td></tr><tr><td>—</td><td>—</td><td><a href="/facts/1/d6SoCnze">100</a></td><td>1</td><td>—</td></tr><tr><td><a href="/facts/Deci-/umQMMcHW">deci</a></td><td>d</td><td><a href="/facts/Orders_of_magnitude_(numbers)/uu2o1hk2">10−1</a></td><td>0.1</td><td rowspan="3">1795</td></tr><tr><td><a href="/facts/Centi-/UhDg8BJG">centi</a></td><td>c</td><td><a href="/facts/Orders_of_magnitude_(numbers)/uu2o1hk2">10−2</a></td><td>0.01</td></tr><tr><td><a href="/facts/Milli-/h1TVNfuW">milli</a></td><td>m</td><td><a href="/facts/Orders_of_magnitude_(numbers)/uu2o1hk2">10−3</a></td><td>0.001</td></tr><tr><td><a href="/facts/Micro-/VXlL1EhM">micro</a></td><td>μ</td><td><a href="/facts/Orders_of_magnitude_(numbers)/uu2o1hk2">10−6</a></td><td>0.000001</td><td>1873</td></tr><tr><td><a href="/facts/Nano-/hzbPWjMK">nano</a></td><td>n</td><td><a href="/facts/Orders_of_magnitude_(numbers)/uu2o1hk2">10−9</a></td><td>0.000000001</td><td rowspan="2">1960</td></tr><tr><td>pico</td><td>p</td><td><a href="/facts/Orders_of_magnitude_(numbers)/uu2o1hk2">10−12</a></td><td>0.000000000001</td></tr><tr><td>femto</td><td>f</td><td><a href="/facts/Orders_of_magnitude_(numbers)/uu2o1hk2">10−15</a></td><td>0.000000000000001</td><td rowspan="2">1964</td></tr><tr><td>atto</td><td>a</td><td><a href="/facts/Orders_of_magnitude_(numbers)/uu2o1hk2">10−18</a></td><td>0.000000000000000001</td></tr><tr><td>zepto</td><td>z</td><td><a href="/facts/Orders_of_magnitude_(numbers)/uu2o1hk2">10−21</a></td><td>0.000000000000000000001</td><td rowspan="2">1991</td></tr><tr><td>yocto</td><td>y</td><td><a href="/facts/Orders_of_magnitude_(numbers)/uu2o1hk2">10−24</a></td><td>0.000000000000000000000001</td></tr><tr><td>ronto</td><td>r</td><td><a href="/facts/Orders_of_magnitude_(numbers)/uu2o1hk2">10−27</a></td><td>0.000000000000000000000000001</td><td rowspan="2">2022</td></tr><tr><td>quecto</td><td>q</td><td><a href="/facts/Orders_of_magnitude_(numbers)/uu2o1hk2">10−30</a></td><td>0.000000000000000000000000000001</td></tr><tr><td colspan="5">Notes</td></tr></tbody></table>