A prefix comes at the start of a word, and helps describe the word.
Prefixes exist for both large and small numbers, and can be seen in everyday life. Examples include kilometre and millimetre.
The prefixes and their corresponding values, both in normal number and standard form, are shown below for both large number and small numbers.
| Prefix | Size | Std form | |
| kilo- | 1,000 | 1 x 103 | |
| mega- | 1,000,000 | 1 x 106 | |
| giga- | 1,000,000,000 | 1 x 109 | |
| tera- | 1,000,000,000,000 | 1 x 1012 |
| Prefix | Size | Std form | |
| pico- | 0.000 000 000 001 | 1 x 10-12 | |
| nano- | 0.000 000 001 | 1 x 10-9 | |
| micro- | 0.000 001 | 1 x 10-6 | |
| milli- | 0.001 | 1 x 10-3 | |
| centi- | 0.01 | 1 x 10-2 | |
| deci- | 0.1 | 1 x 10-1 |
An engineering company makes a very small part which is a component of some medical equipment. The part consists of six layers of metal, which are each 2.4 nM (nanometers) thick. Write the overall thickness of the part in standard form.
6 layers x 2.4 x 10-9
14.4 x 10-9
1.44 x 10-8
Answer: 1.44 x 10-8m
One Astronomical Unit is about 150 gigametres, which is the distance from the earth to the sun. Write this number in standard form.
150 x 109
=1.5 x 1011
Answer: 1.5 x 1011
See also Calculating with Indices