Mega-

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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

Other common examples of usage

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 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)

Computing

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.

Metric prefixes
Prefix Symbol 1000m 10n Decimal English word Sincen 1
short scale long scale
yotta Y  10008  1024 1000000000000000000000000  septillion  quadrillion 1991
zetta Z  10007  1021 1000000000000000000000  sextillion  thousand trillion 1991
exa E  10006  1018 1000000000000000000  quintillion  trillion 1975
peta P  10005  1015 1000000000000000  quadrillion  thousand billion 1975
tera T  10004  1012 1000000000000  trillion  billion 1960
giga G  10003  109 1000000000  billion  thousand million 1960
mega M  10002  106 1000000             million 1960
kilo k  10001  103 1000             thousand 1795
hecto h  10002/3  102 100             hundred 1795
deca da  10001/3  101 10             ten 1795
 10000  100 1             one
deci d  1000−1/3  10−1 0.1             tenth 1795
centi c  1000−2/3   10−2 0.01             hundredth 1795
milli m  1000−1  10−3 0.001             thousandth 1795
micro µ  1000−2  10−6 0.000001             millionth 1960
nano n  1000−3  10−9 0.000000001  billionth  thousand millionth 1960
pico p  1000−4  10−12 0.000000000001  trillionth  billionth 1960
femto f  1000−5  10−15 0.000000000000001  quadrillionth  thousand billionth 1964
atto a  1000−6  10−18 0.000000000000000001  quintillionth  trillionth 1964
zepto z  1000−7  10−21 0.000000000000000000001  sextillionth  thousand trillionth 1991
yocto y  1000−8  10−24  0.000000000000000000000001  septillionth  quadrillionth  1991
  1. ^ The metric system was introduced in 1795 with six prefixes. The other dates relate to recognition by a resolution of the CGPM.

See also

References

  1. ^ "[http://dictionary.oed.com/cgi/entry/00304790 mega-]". Oxford English Dictionary (3rd ed.). Oxford University Press. September 2005. 

External links








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