Metric Prefixes

Metric Prefixes are Multipliers

SI also simplifies numbers that are large and small with metric prefixes. These prefixes are multipliers for scaling the unit to which they are attached. Here are two examples:

scale for 1,000

  • prefix name:  kilo
  • prefix symbol: k        

scale for 0.001

  • prefix name: milli
  • prefix symbol: m

Metric prefixes make it so that you can write 20 km instead of 20,000 m, and 3 mm instead of 0.003 m.

In these examples:

  • 20 km is equivalent to 20 x 1000 m
  • 3 mm is equivalent to 3 x 0.001 m

Here is a table with the common metric prefixes these lessons will use.

SI Metric Prefixes (Multipliers)
Quantity Prefix Decimal
English Name Name Symbol Value Scientific Notation
Billion giga G 1,000,000,000 x 109
Million mega M 1,000,000 x 106
Thousand kilo k 1,000 x 103
Thousandth milli m 0.001 x 10-3
Millionth micro µ 0.000001 x 10-6
Billionth nano n 0.000000001 x 10-9
Trillionth pico p 0.000000000001 x 10-12

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