Byte

Mega- (symbol M) is an prefix in the metric system denoting a factor of million (10⁶ or 1000000). Confirmed in 1960, it comes from the Greek μέγας, meaning great.

Other common examples of usage

• 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.

Exponentiation

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 1,000,000 m by 1,000,000 m or 10¹² m², and not 1,000,000 square metres (10⁶ m²).
• 1 Mm³ means one cubic megametre or the size of a cube of 1,000,000 m by 1,000,000 m by 1,000,000 m or 10¹⁸ m³, and not 1,000,000 cubic metres (10⁶ m³)

Computing

In computing, mega can sometimes denote 1,048,576 (2²⁰) of information units (example: a megabyte, a megaword), but can denote 1,000,000 (10⁶) 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 2²⁰ to avoid ambiguity.

See also

• SI prefix
• Binary prefix
• Mebibyte
• Orders of magnitude

References

1. ^ "[http://dictionary.oed.com/cgi/entry/00304790 mega-]". Oxford English Dictionary. Oxford University Press. 3rd ed. 2001.

External links

Look up mega- in Wiktionary, the free dictionary.

• BIPM website