Electrical quantities such as resistance, voltage, power, inductance and capacitance can have very large values. For example a power station can generate 1,000,000,000 watts of power, similarly an inductor can have a value of 0.00001 H. To keep things straight forward, a common practice is to use prefixes. Each prefix represents a power of ten. The table below display top 7 prefixes that are very common in Electrical and Electronics Engineering.
| Number | Power of 10 | Prefix | Symbol |
| 1 000 000 000 | 109 | giga | G |
| 1 000 000 | 106 | mega | M |
| 1 000 | 103 | kilo | k |
| 0.001 | 10-3 | milli | m |
| 0.000 001 | 10-6 | micro | μ |
| 0.000 000 001 | 10-9 | nano | n |
| 0.000 000 000 001 | 10-12 | pico | p |
Examples
Example 1: Express 33000 V in kilovolts.
Solution: Multiply and divide the number by 1000
= 33000 V * (1000/1000)
= (33000/1000) V * 1000
= 33 kV
Example 2: Express 0.222 A in milliAmps.
Solution: Multiply and divide the number by 0.001.
= 0.222 * (0.001/0.001) A
= 0.222 * (m/0.001) A
= (0.222/0.001) mA
= 222 mA