Mega is a unit prefix in metric systems of units denoting a factor of one million (106 or 1000000). It has the unit symbol M. It was confirmed for use in the International System of Units (SI) in 1960. Mega comes from Ancient Greek: μέγας, romanizedmégas, lit.'great'.[1]

Common examples of usage

Exponentiation

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

Computing

In some fields of computing, mega may sometimes denote 1,048,576 (220) of information units, for example, a megabyte, a megaword, but denotes 1000000 (106) units of other quantities, for example, transfer rates: 1megabit/s = 1000000bit/s. The prefix mebi- has been suggested as a prefix for 220 to avoid ambiguity.

Prefix Base 10 Decimal Adoption
[nb 1]
Name Symbol
quetta Q 1030 1000000000000000000000000000000 2022
ronna R 1027 1000000000000000000000000000 2022
yotta Y 1024 1000000000000000000000000 1991
zetta Z 1021 1000000000000000000000 1991
exa E 1018 1000000000000000000 1975
peta P 1015 1000000000000000 1975
tera T 1012 1000000000000 1960
giga G 109 1000000000 1960
mega M 106 1000000 1873
kilo k 103 1000 1795
hecto h 102 100 1795
deca da 101 10 1795
100 1
deci d 10−1 0.1 1795
centi c 10−2 0.01 1795
milli m 10−3 0.001 1795
micro μ 10−6 0.000001 1873
nano n 10−9 0.000000001 1960
pico p 10−12 0.000000000001 1960
femto f 10−15 0.000000000000001 1964
atto a 10−18 0.000000000000000001 1964
zepto z 10−21 0.000000000000000000001 1991
yocto y 10−24 0.000000000000000000000001 1991
ronto r 10−27 0.000000000000000000000000001 2022
quecto q 10−30 0.000000000000000000000000000001 2022
Notes
  1. ^ Prefixes adopted before 1960 already existed before SI. The introduction of the CGS system was in 1873.

See also

References

  1. ^ "Oxford English Dictionary (OED Online)". www.oed.com (3rd ed.). Oxford University Press. June 2001. Retrieved 2017-09-18. Origin: A borrowing from Greek. Etymon: Greek μεγα-. ... Forming scientific and technical terms with the sense ‘very large’, ‘comparatively large’, or (esp. in Pathol.) ‘abnormally large’, often having correlatives beginning micro-, and sometimes also synonyms beginning macro-.