The SI units are the standard units that we use to measure both fundamental and derived quantities.
Multiples and submultiples
Multiples help us to represent large numbers without having to write many digits.
| Multiple prefix | Symbol | Value | Value expressed as a power of 10 |
|---|---|---|---|
| Kilo- | k | 1,000 | $10^3$ |
| Mega- | M | 1,000,000 | $10^6$ |
| Giga- | G | 1,000,000,000 | $10^9$ |
| Tera- | T | 1,000,000,000,000 | $10^{12}$ |
Notice that the prefixes are simply placeholders for positive (+ve) powers of 10.
Submultiples
Submultiples allow us to represent small numbers without the need to write many digits.
| Submultiple prefix | Symbol | Value | Value expressed as a power of 10 |
|---|---|---|---|
| Milli- | m | 0.001 | $10^{-3}=\frac{1}{10^3}=\frac{1}{1,000}$ |
| Micro- | $\mu$ | 0.000001 | $10^{-6}=\frac{1}{1,000,000}$ |
| Nano- | n | 0.000000001 | $10^{-9}=\frac{1}{1,000,000,000}$ |
| Pico- | p | 0.000000000001 | $10^{-12}=\frac{1}{1,000,000,000,000}$ |