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, cancels down by a factor of two to make so equals 71%. Alternatively you might cancel a fraction down to one you have memorised from the list above, e.g. simplifies by a factor of two to make 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 becomes or 26% when you multiply numerator and denominator by two. You might also need a combination of these methods, for example cancels down by a factor of three to make , which can then be built up to 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.
If you have comments or queries about this sheet, or are looking for additional support in this area, please contact me.