Deca-

Deca- or deka-[1] (symbol da) is a prefix in the metric system, also a numerical prefix, denoting a factor of ten. The term is derived from the Greek δέκα meaning "ten". Its symbol is the only SI prefix that uses more than one character.

The prefix was a part of the original metric system in 1795. It is not in very common usage, although the decapascal is occasionally used by audiologists. The decanewton is also encountered occasionally, probably because it is an SI approximation of the kilogram-force. It is more commonly used in other languages: in Austrian, Slovak and Hungarian, deca is common (and always means decagram).

Before the symbol was standardized as da with the introduction of the International System of Units in 1960, various other symbols were more common, such as "dk", "D", and "Da".

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.

References

  1. ^ Guide for the Use of the International System of Units (SI), 1995, NIST Special Publication 811

See also

External links