POWERS OF TEN
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“power of 10 ”
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means 10 raised to some number; e.g.:
102 = 10  10
105 = 10  10  10  10  10
10n = n factors of 10; n = “exponent”
scientific notation:
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express numbers as: a  10n ,
where a is a number “of order 1”
(i.e. between 1 and 10)
negative exponent:
10-n means 1/(10n)
to multiply two powers, add their exponents:
102  105 = 107
thousand = 103 , million = 106
common prefixes used to denote powers of ten:
3
 kilo (k) = 10 ,
6
 Mega (M) = 10 ,
9
 Giga (G) = 10
12
 Tera (T) = 10
-3
 milli (m) = 10
,
-6
 micro () = 10
-9
 nano (n) = 10
-12
 pico (p) = 10
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“Metric units”
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Units
apart from few exceptions, “metric units”, or
rather “SI units” are used throughout the world;
(“SI” stands for “Système International”,
maintained by the “Societé Internationale des Poids
et Mesures”, = international society of weights and
measures, with seat in Sèvres near Paris)
basic units are, e.g.: meter for distance, kilogram
for mass, second for time;
meter originally defined as 1/(4  107)  length of
Earth's meridian; now defined in terms of speed of
light;
some common distance units:
3
 kilometer, km = 10 m,
-2
 centimeter, cm = 10
m,
-3
 millimeter, mm = 10
m,
-6
 micrometer, µm = 10
m,
-9
 nanometer, nm, 10 m
“metric” vs “English” distance units:
 1 km  0.62 mi, 1mi  1.6 km,
 1 m  3.3 ft  39 in,
 1cm  0.39 in, 1 in = 2.54 cm