# Deci-

Deci (symbol d) is a decimal unit prefix in the metric system denoting a factor of one tenth. Proposed in 1793,[1] and adopted in 1795, the prefix comes from the Latin decimus, meaning "tenth". Since 1960, the prefix is part of the International System of Units (SI).[2][3]

A frequent use of the prefix is in the unit deciliter (dl), common in food recipes; many European homes have a deciliter measure for flour, water, etc. A common measure in engineering is the unit decibel for measuring ratios of power and root-power quantities, such as sound level and electrical amplification.

Example
• The diameter of a compact disc is about 12 centimetres or 1.2 decimetres.[4]
Prefix Base 10 Decimal English word Adoption[nb 1] Etymology
Name Symbol Short scale Long scale Language Derived word
yotta Y 1024 1000000000000000000000000 septillion quadrillion 1991 Greek eight[nb 2]
zetta Z 1021 1000000000000000000000 sextillion trilliard 1991 Latin seven[nb 2]
exa E 1018 1000000000000000000 quintillion trillion 1975 Greek six
peta P 1015 1000000000000000 quadrillion billiard 1975 Greek five[nb 2]
tera T 1012 1000000000000 trillion billion 1960 Greek four,[nb 2] monster
giga G 109 1000000000 billion milliard 1960 Greek giant
mega M 106 1000000 million 1873 Greek great
kilo k 103 1000 thousand 1795 Greek thousand
hecto h 102 100 hundred 1795 Greek hundred
deca da 101 10 ten 1795 Greek ten
100 1 one
deci d 10−1 0.1 tenth 1795 Latin ten
centi c 10−2 0.01 hundredth 1795 Latin hundred
milli m 10−3 0.001 thousandth 1795 Latin thousand
micro μ 10−6 0.000001 millionth 1873 Greek small
nano n 10−9 0.000000001 billionth milliardth 1960 Greek dwarf
pico p 10−12 0.000000000001 trillionth billionth 1960 Spanish peak
femto f 10−15 0.000000000000001 quadrillionth billiardth 1964 Danish fifteen, Fermi[nb 3]
atto a 10−18 0.000000000000000001 quintillionth trillionth 1964 Danish eighteen
zepto z 10−21 0.000000000000000000001 sextillionth trilliardth 1991 Latin seven[nb 2]
yocto y 10−24 0.000000000000000000000001 septillionth quadrillionth 1991 Greek eight[nb 2]
1. ^ Prefixes adopted before 1960 already existed before SI. The introduction of the CGS system was in 1873.
2. Part of the beginning of the prefix was modified from the word it was derived from, ex: "peta" (prefix) vs "penta" (derived word).
3. ^ The fermi was introduced earlier with the same symbol "fm", in which then the "f" became a prefix. The Danish word is used since it is vaguely spelled similar to fermi.

## References

1. ^ Commission temporaire de Poids & Mesures rêpublicaines, En exécution des Décrets de la Convention Nationale (1793). Instruction abrégée sur les mesures déduites de la grandeur de la Terre; uniformes pour toute la Rêpublique, et sur les Calculs relatifs à leur division décimale (in French) (Edition originale ed.). Paris, France: De l´imprimerie nationale exécutive du Louvre. Retrieved 2015-10-09.
2. ^ The International System of Units (Si): The Metric System. DIANE Publishing. 1992. p. 30. ISBN 9780941375740.
3. ^ "Resolution 12 of the 11th CGPM". BIPM. 1960. Retrieved 2020-05-14.
4. ^ "Universcale: From the nanoworld to the universe — The worlds we measure using our infinite yardstick". Nikon. 2013. Archived from the original on 2017-02-08. Retrieved 2017-02-08.