# Mega-

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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, romanized: mégas, lit.  'great'. 

## 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.

• 1 Mm2 means one square megametre or the size of a square of 1000000m by 1000000m or 1012m2, and not 1000000 (106 m2).
• 1 Mm3 means one cubic megametre or the size of a cube of 1000000m by 1000000m by 1000000m or 1018 m3, and not 1000000 (106 m3)

## 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 = 1000000. The prefix mebi- has been suggested as a prefix for 220 to avoid ambiguity.

SI prefixes
PrefixBase 10 Decimal English wordAdoption [nb 1]
NameSymbol Short scale Long scale
yotta Y  1024 1000000000000000000000000 septillion quadrillion1991
zetta Z  1021 1000000000000000000000 sextillion trilliard1991
exa E  1018 1000000000000000000 quintillion trillion1975
peta P  1015 1000000000000000 quadrillion billiard1975
tera T  1012 1000000000000 trillion billion1960
giga G  109 1000000000 billion milliard1960
mega M  106 1000000 million1873
kilo k  103 1000 thousand1795
hecto h  102 100 hundred1795
deca da  101 10 ten1795
100 1 one
deci d  10−1 0.1 tenth1795
centi c  10−2 0.01 hundredth1795
milli m  10−3 0.001 thousandth1795
micro μ  10−6 0.000001 millionth1873
nano n  10−9 0.000000001 billionth milliardth1960
pico p  10−12 0.000000000001 trillionth billionth1960
femto f  10−15 0.000000000000001 quadrillionth billiardth1964
atto a  10−18 0.000000000000000001 quintillionth trillionth1964
zepto z  10−21 0.000000000000000000001 sextillionth trilliardth1991
yocto y  10−24  0.000000000000000000000001 septillionth quadrillionth1991
1. Prefixes adopted before 1960 already existed before SI. The introduction of the CGS system was in 1873.

## Related Research Articles

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The megabit is a multiple of the unit

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1. . 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-.