# Multiples and sub-multiples, abbreviations and indices

The metre is the fundamental unit of length; for convenience we often use the term kilometre (greater than one metre- a multiple) or millimetre (less than one Metre- a sub-multiple). The same system is used with all electrical units.

Multiple | Sub-multiple | Abbreviation | Meaning | Example
giga | - | G | x109 | GHz
mega | - | M | x106 | MW
kilo | - | k | x103 | kV
- | milli | m | x10-3 | mA
- | micro |  | x10-6 | H
- | nano | n | x10-9 | ns
- | pico | p | x10-12 | pF

With the exception of 'kilo', multiples use capital letters and sub-multiples small letters in the abbreviations.

103 means 'times 1000', i.e. 1 km = l000m; the index 3 indicates the number of places the decimal point must be moved to the right. Similarly 10-3 means 'divided by 1000', i.e. 1 mm = 0.001 m; the index -3 indicates the number of places the decimal point must be moved to the left.

Multiplication-add indices; division-subtract indices (for a common base).

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