Chapter 6: Percentages and financial mathematics

The chapter problem

An account starts with £600 and earns 4% compound interest each year. Predict its balance after two years. Will it be more than £640? Make a prediction before calculating.

By the end of this chapter

• Find a percentage of an amount and calculate a percentage change.
• Recover an original amount after a percentage change.
• Calculate simple and compound interest.
• Model repeated growth and decay with a multiplier.

Roadmap

1. 6.1 Percentage of an amount
2. 6.2 Percentage change
3. 6.3 Reverse percentages
4. 6.4 Simple and compound interest
5. 6.5 Growth, decay and repeated percentage change
6. Review

Your turn to connect it

A percentage may appear in a sale, a bill, a savings account or a change in population. Which situation matters to you or someone you know? Write one example and say what you would want to calculate.

Use each section to learn a method, practise with support, then try independent questions. The Review returns to your savings prediction and mixes methods from this chapter with earlier work.