To change the subject of a formula is to rearrange it so that a different letter is on its own on the left hand side. This is one of the important skills you can learn in Maths. The methods required here reappear in many other aspects of Maths, including solving equations, trigonometry, Pythagoras' theorem, nth term and many others. Rearranging formulae is also an essential part of most calculations in other sciences such as Chemistry and Physics.

For some of the questions, there may be more than one way of writing the answer. If your answer is different from that show in the answers section, check to see if they can be rearranged to make them the same (e.g. by multiplying through by -1).