For many subjects you should know base quantity (measurement types) and their base/international units (the base units the measurements are measured in internationally). These are shown below:
- Length – Metre (m)
- Mass – Kilogram(Kg)
- Time – Seconds (s)
- Electric Current – Amperes/Amps (A)
- Temperature – Kelvin (K)
- Amount of substance – Moles (mol)
Make sure you learn these.
For super large or super small numbers we also use prefixes. For example, one thousand grams is called a kilogram. The prefix here is kilo which is a multiplying factor of a thousand. A kilo is abbreviated to the letter k. For many courses you must learn the following prefixes off by heart. You should also know what each prefix abbreviation stands for. Below shows each prefix name – the abbreviation – and the multiplying factor.
- Femto = f = 10^-15
- Pico = p = 10^-12
- Nano = n = 10^-9
- Micro = μ = 10^-6
- milli = m = 10^-3
- Kilo = k = 10^3
- Mega = M = 10^6
- Giga = G = 10^9
- Tera = T = 10^12
Notice that some of the abbreviations have Lower and some Upper case- Do not confuse the two.
An example of using these prefixes:
3.9nA = 3.9 nano Amps = 3.9 x 10^-9 Amps