# Section 3 - Technical Basics

## 3.1 Units

In the scientific and engineering worlds it is very common for the normal units of measure to be very small or very large. Often we must use alternative units in order to save ourselves from writing loads of zero's.

Consider for a moment the standard unit of weight which is the gram. A gram is a very small weight so in everyday life we more often use the kilogram. One kilogram is equal to a thousand grams. However, when dealing with powerful drugs a gram would be far too much, so we use milligrams, meaning one thousandth of a gram. There are one thousand milligrams in a gram.

There are many such shorthand ways of writing very big or very small numbers. For the foundation licence we need only know three.

"milli", meaning thousandth, 1/1000 or 0.01, is written "m" e.g.100mV = 100 x 0.01V = 0.1V, 5mA = 5 x 0.01A = 0.05A

"Kilo", meaning thousand, is written "K" e.g. 1KV = 1000 Volts, and 27K = 27,000

"Mega" meaning million, is written "M" e.g. 26M = 26,000,000.

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