# Calculating percentages practice worksheet for QTS Numeracy mental arithmetic

Calculating percentages is a common question in the mental arithmetic section of the QTS Numeracy test. Solving these problems is much easier if you have memorised your list of important fraction-decimal-percentage conversions.

For some questions you can immediately cancel down to a fraction out of 100, and this gives you the percentage. For instance, $\frac {142}{200}$ cancels down by a factor of two to make $\frac {71}{100}$ so equals 71%. Alternatively you might cancel a fraction down to one you have memorised from the list above, e.g. $\frac{10}{16}$ simplifies by a factor of two to make $\frac 5 8$ which is 62.5% — many mental questions involve the eighths so it is best to learn their percentage conversions by heart!

Other times you need to build a fraction up, for instance $\frac{13}{50}$ becomes $\frac{26}{100}$ or 26% when you multiply numerator and denominator by two. You might also need a combination of these methods, for example $\frac{27}{75}$ cancels down by a factor of three to make $\frac{9}{25}$, which can then be built up to $\frac{36}{100}$ or 36% by multiplying numerator and denominator by four.

This worksheet, with answers on the second page, includes questions that require a mixture of these methods. Follow this link for more free QTS Numeracy resources.