  One question presents a formula that converts degrees Celsius (centigrade) to degrees Fahrenheit.

# Formulas (H)

Rearranging complicated formula could be considered as the pinnacle of algebra skills. Are you at the Everest of your algebraic manipulation skills? Find out in this GCSE Maths quiz.

Formulas (or formulae) are very useful in all aspects of life, but particularly to scientists and engineers. Once a formula has been derived, it means that future scientists and engineers don’t have to rediscover it for themselves. If you study Physics you will be familiar with Newton’s second law, F=ma. Imagine if you had to work out this relationship every time you tried to solve a force problem – you would soon not bother!

There are two key skills about using formula. The first is substitution – when you are given the value of a variable, you replace the variable with this number each time it occurs in the formula.

Substitution occurs in many other areas of algebra, so you should already be familiar with it.

The second skill is rearranging a formula. Formulae tend to be stated and remembered in one arrangement. For instance, you should recall that the formula for the volume of a cylinder is V = πr2h. This is fine if you know r and h. But what if you are given the volume, V, and the height, h, and need to find r? You will need to rearrange the formula so that r is the subject. Can you master it?

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