Mega is a unit prefix in the metric system denoting a factor of one million (106 or 1000000). It was confirmed for use in the International System of Units (SI) in 1960. Mega comes from the Greek μέγας, meaning great.1
- megapixel - 1 million pixels in a digital camera
- one megatonne (of TNT) (a unit often used in measuring the explosive power of nuclear weapons) is the approximate energy released on igniting one million tonnes of TNT.
- megahertz — frequency of electromagnetic radiation for radio and television broadcasting, GSM, etc. 1 MHz = 1,000,000 Hz.
When units occur in exponentiation, such as in square and cubic forms, any size 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 1000000square metres (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 1000000cubic metres (106 m3)
In computing, mega may sometimes denote 1,048,576 (220) of information units (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.
- "[http://dictionary.oed.com/cgi/entry/00304790 mega-]". Oxford English Dictionary (3rd ed.). Oxford University Press. September 2005.
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