Hecto-

Hecto or hecta (symbol h) is a prefix in the metric system denoting a factor of one hundred. Adopted in 1795, it comes from the Greek ἑκατόν hekaton, meaning hundred.

It is rarely used, except for certain specific applications:

SI prefixes
Prefix Symbol 1000m 10n Decimal Short scale Long scale Scientific notation Since[n 1]
yotta Y 10008 1024 1000000000000000000000000 Septillion Quadrillion 1E24 1991
zetta Z 10007 1021 1000000000000000000000 Sextillion Trilliard 1E21 1991
exa E 10006 1018 1000000000000000000 Quintillion Trillion 1E18 1975
peta P 10005 1015 1000000000000000 Quadrillion Billiard 1E15 1975
tera T 10004 1012 1000000000000 Trillion Billion 1E12 1960
giga G 10003 109 1000000000 Billion Milliard 1E9 1960
mega M 10002 106 1000000 Million 1E6 1960
kilo k 10001 103 1000 Thousand 1E3 1795
hecto h 10002/3 102 100 Hundred 1E2 1795
deca da 10001/3 101 10 Ten 1E1 1795
10000 100 1 One – –
deci d 1000−1/3 10−1 0.1 Tenth 1E-1 1795
centi c 1000−2/3 10−2 0.01 Hundredth 1E-2 1795
milli m 1000−1 10−3 0.001 Thousandth 1E-3 1795
micro μ 1000−2 10−6 0.000001 Millionth 1E-6 1960
nano n 1000−3 10−9 0.000000001 Billionth Milliardth 1E-9 1960
pico p 1000−4 10−12 0.000000000001 Trillionth Billionth 1E-12 1960
femto f 1000−5 10−15 0.000000000000001 Quadrillionth Billiardth 1E-15 1964
atto a 1000−6 10−18 0.000000000000000001 Quintillionth Trillionth 1E-18 1964
zepto z 1000−7 10−21 0.000000000000000000001 Sextillionth Trilliardth 1E-21 1991
yocto y 1000−8 10−24 0.000000000000000000000001 Septillionth Quadrillionth 1E-24 1991
  1. ^ The metric system was introduced in 1795 with six prefixes. The other dates relate to recognition by a resolution of the CGPM.

See also