formula (formulae)

A formula is made up of numbers and symbols which show how to work something out. It shows the relationship between two or more variables.

A formula is often written so that one variable is on the left-hand side and the way of calculating that variable is shown on the right-hand side.

An example is the formula for calculating the area A of a circle when the radius r of the circle is known:

\textmd {Area} = \pi \times r^{2}

      \textmd {A} = \pi r^{2}