Metric notation
The metric system, besides being a collection of measurement
units for all sorts of physical quantities, is structured around the
concept of scientific notation. The primary difference is that the
powers-of-ten are represented with alphabetical prefixes instead of
by literal powers-of-ten. The following number line shows some of
the more common prefixes and their respective powers-of-ten:
Looking at this scale, we can see that 2.5 Gigabytes would mean
2.5 x 109 bytes, or 2.5 billion bytes. Likewise, 3.21
picoamps would mean 3.21 x 10-12 amps, or 3.21
1/trillionths of an amp.
Other metric prefixes exist to symbolize powers of ten for
extremely small and extremely large multipliers. On the extremely
small end of the spectrum, femto (f) = 10-15,
atto (a) = 10-18, zepto (z) = 10-21,
and yocto (y) = 10-24. On the extremely large end
of the spectrum, Peta (P) = 1015, Exa (E) =
1018, Zetta (Z) = 1021, and Yotta
(Y) = 1024.
Because the major prefixes in the metric system refer to powers
of 10 that are multiples of 3 (from "kilo" on up, and from "milli"
on down), metric notation differs from regular scientific notation
in that the significant digits can be anywhere between 1 and 1000,
depending on which prefix is chosen. For example, if a laboratory
sample weighs 0.000267 grams, scientific notation and metric
notation would express it differently:
2.67 x 10-4 grams (scientific notation)
267 µgrams (metric notation)
The same figure may also be expressed as 0.267 milligrams (0.267
mg), although it is usually more common to see the significant
digits represented as a figure greater than 1.
In recent years a new style of metric notation for electric
quantities has emerged which seeks to avoid the use of the decimal
point. Since decimal points (".") are easily misread and/or "lost"
due to poor print quality, quantities such as 4.7 k may be mistaken
for 47 k. The new notation replaces the decimal point with the
metric prefix character, so that "4.7 k" is printed instead as
"4k7". Our last figure from the prior example, "0.267 m", would be
expressed in the new notation as "0m267".
- REVIEW:
- The metric system of notation uses alphabetical prefixes to
represent certain powers-of-ten instead of the lengthier
scientific notation.
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