kilo-

From Wikipedia, the free encyclopedia

This is an old revision of this page, as edited by Compvis (talk | contribs) at 06:52, 2 April 2014 (Expansion on the definition.). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

For other uses, see Kilo (disambiguation).


Look up kilo- in Wiktionary, the free dictionary.

kilo is a unit prefix in the metric system denoting multiplication by one thousand. It has been used in the International System of Units where it has the unit symbol k, in lower case.

The prefix kilo is derived from the Greek word χίλιοι (chilioi), meaning "thousand". It was originally adopted by Antoine Lavoisier's research group in 1795, and introduced into the metric system in France with its establishment in 1799.

Examples:

A second definition has been used incoherently in some contexts of computer science and information technology, which is, however, inconsistent with the SI. It uses kilo as meaning 210 = 1024, because of the mathematical coincidence that 210 is approximately 103. The incoherence of that definition is that it suggests that kilobyte can sometimes mean 1024 bytes, whereas "kilo" in kilobit always implies a decimal multiple, exactly as in every other unit using the kilo prefix. The NIST comments on this confusion: "Faced with this reality, the IEEE Standards Board decided that IEEE standards will use the conventional, internationally adopted, definitions of the SI prefixes", instead of kilo for 1024.[1]

Example:

  • One "Kilobyte" (KB) is 1024 bytes in JEDEC-standard, whereas the definition has shifted to, in most contexts, mean 1000 bytes (kB) in accordance with SI.

Exponentiation

When units occur in exponentiation, such as in square and cubic forms, any multiplier prefix is considered part of the unit, and thus included in the exponentiation.

  • 1 km2 means one square kilometre or the area of a square that measures 1000 m on each side or 106 m2 (as opposed to 1000 square meters, which is the area of a square that measures 31.6 m on each side).
  • 1 km3 means one cubic kilometre or the volume of a cube that measures 1000 m on each side or 109 m3 (as opposed to 1000 cubic meters, which is the volume of a cube that measures 10 m on each side).

See also

References

  1. ^ Definition of binary prefixes at NIST
SI prefixes
Prefix Base 10 Decimal Adoption
[nb 1]
Name Symbol
quetta Q 1030 1000000000000000000000000000000 2022[1]
ronna R 1027 1000000000000000000000000000
yotta Y 1024 1000000000000000000000000 1991
zetta Z 1021 1000000000000000000000
exa E 1018 1000000000000000000 1975[2]
peta P 1015 1000000000000000
tera T 1012 1000000000000 1960
giga G 109 1000000000
mega M 106 1000000 1873
kilo k 103 1000 1795
hecto h 102 100
deca da 101 10
— — 100 1 —
deci d 10−1 0.1 1795
centi c 10−2 0.01
milli m 10−3 0.001
micro μ 10−6 0.000001 1873
nano n 10−9 0.000000001 1960
pico p 10−12 0.000000000001
femto f 10−15 0.000000000000001 1964
atto a 10−18 0.000000000000000001
zepto z 10−21 0.000000000000000000001 1991
yocto y 10−24 0.000000000000000000000001
ronto r 10−27 0.000000000000000000000000001 2022[1]
quecto q 10−30 0.000000000000000000000000000001
Notes
  1. ^ Prefixes adopted before 1960 already existed before SI. The introduction of the CGS system was in 1873.
  1. ^ a b "On the extension of the range of SI prefixes". 18 November 2022. Retrieved 5 February 2023.
  2. ^ "Metric (SI) Prefixes". NIST.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Kilo-&oldid=602381442"