Mega-
19938
223126139
2008-07-02T18:09:46Z
EmersonLowry
1741227
changed a square symbol to a cube symbol.
{{lowercase}}
{{wiktionary|mega-}}
{{otheruses|Mega}}
'''mega-''' (symbol '''M''') is an [[SI prefix]] in the [[SI]] system of [[Units of measurement|unit]]s denoting a factor of [[1 E6|10<sup>6</sup>]], 1,000,000 (one [[million]]).
For example, 1 MW (megawatt) = 1,000,000 [[watt]]s = 1,000 [[kilowatt]]s.
Confirmed in 1960, it comes from the [[Greece|Greek]] μέγας, meaning ''great''.<ref>{{OED|[http://dictionary.oed.com/cgi/entry/00304790 mega-]}}</ref>
==Other common examples of usage==
* one [[megaton]] [of TNT] (a unit often used in measuring the explosive power of [[nuclear weapon]]s) is 1,000,000 tons of TNT.
* [[megahertz]] — frequency of [[electromagnetic radiation]] for radio and television broadcasting, [[GSM]], etc. 1 MHz = 1,000,000 [[Hertz|Hz]].
==Square and cubic forms==
As the SI-prefixes take precedence over exponents,
* 1 Mm² means one square [[megametre]] or the size of a [[Square (geometry)|square]] of 1,000,000 m × 1,000,000 m or <math>10^{12}</math> m² (and not 1,000,000 × a [[square metre]] or <math>10^{6}</math> m²)
* 1 Mm³ means one cubic [[megametre]] or the size of a [[cube]] of 1,000,000 m × 1,000,000 m × 1,000,000 m or <math>10^{18}</math> m² (and not 1,000,000 × a [[cubic metre]] or <math>10^{6}</math> m³)
==Computing==
In [[computing]], mega- can sometimes denote 1,048,576 (2<sup>20</sup>) of information units (example: a [[megabyte]], a megaword), but can denote 1,000,000 (10<sup>6</sup>) of other quantities, for example, transfer rates: 1 megabit/s = 1,000,000 [[bit/s]].
The prefix ''[[mebi]]-'' has been suggested as a prefix for 2<sup>20</sup> to avoid ambiguity, but is yet to be widely used.
{{SI prefixes}}
==See also==
*[[SI prefix]]
*[[Binary prefix]]
*[[Mebibyte]]
*[[Orders of magnitude]]
==References==
<references/>
==External links==
*[http://www.bipm.org BIPM website]
[[Category:SI prefixes]]
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