Percentage Changes

Further Ideas

This topic can be explored further by investigating the following questions:

You have a Saturday job and are able to claim a staff discount of 10% on the purchase of goods. All goods attract VAT at 17.5%. Given the choice, would you ask for the VAT to be added before or after you claim your staff discount?

What if additionally the goods were to be reduced by 20% in a sale? What would be the order of calculation you would choose now?

Does the order of calculation matter to HM Customs and Excise?

The unitary method of finding 1% (which was used in the programme to work out the number of free biscuits) can be applied practically. Ask students to suggest methods of finding 1% in a range of contexts. For example, how would they find 1% of...?

• a piece of string
• a sheet of A4 paper
• a canned drink or box of cereal
• their text book
• 20 minutes
• the total secondary-school population
• £8, £825, £8.25

This work is easily extended to finding other percentages and equivalent fractions.