Percentage Changes

Overview

Sales and special offers in the high street provide an opportunity to explore percentage increases and decreases. We see how to:

• calculate a discount
• work out a percentage change
• compare different offers expressed as percentages
• find the original value of something before a percentage change

The content is linked to the requirements of GCSE Intermediate Mathematics. It includes tips for answering exam questions, and a discussion of a typical exam error ('Tick or Trash'). The programme uses familiar contexts that students will have met in real life. It assumes a basic understanding of how to calculate a percentage of a quantity and how to convert a fraction to a percentage. Common fraction-percentage equivalents are used, and both mental and mechanical means of calculation are illustrated.

The programme could be used either as an introduction to more involved calculations with percentage changes, or as revision of the types of problems that may be set within the topic and their methods of solution.