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Prefixes

A prefix is a power of ten with a name. Kilo is one thousand, that is 10 to the third. Mega is one million and giga one billion. Milli is one thousandth and micro one millionth. You convert by multiplying by the power the prefix stands for. Small numbers in standard form have a negative exponent. A number with several zeros after the decimal point is small, and the standard form has one digit before the point.

kilo=103\text{kilo} = 10^3one thousand
milli=10−3\text{milli} = 10^{-3}one thousandth
micro=10−6\text{micro} = 10^{-6}one millionth

Symbols

10310^3kilo
10−510^{-5}five places below 1

Example

3 km is 3⋅103=30003 \cdot 10^3 = 3000 m.

0.00003=3⋅10−50.00003 = 3 \cdot 10^{-5}.

A positive exponent moves the decimal point to the right. A negative exponent moves it to the left.
Practise powers and standard form for free →

← Rules of powers

Part of Mathematics 2P: Powers and standard form.