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This topic covers repeated percentage change over time — growth and decay — using multipliers raised to a power, applied to savings, depreciation and populations. It's examined right across GCSE and iGCSE Maths. Work through it free on eClassroom, with clear worked examples and instantly-marked questions that build your confidence for the exam.
How you do it
Find the multiplier for one time period, then raise it to the power of the number of periods. Multiply the starting amount by that. Growth gives a multiplier above 1 and decay below it.
Before you start
The groundwork here is percentage multipliers and indices. It sets up compound interest and exponential models.
What you learn
Compound growth and decay apply a percentage change again and again, each time to the new amount. Savings grow with compound interest; cars and phones lose value through depreciation. With compound interest, each year’s interest is added on, and the next year’s interest is worked out on the larger amount. Decay works the same way but the amount falls. With simple interest the same amount is added every year (interest only on the original). The course works through compound growth, compound decay (depreciation) and simple versus compound. Every section has instant-feedback practice questions matched to Edexcel iGCSE 4MA1 and the other major GCSE boards, and the course finishes with full exam-style questions you mark yourself.
Related Topics
We teach Growth & Decay as one of the Ratio and Proportion topics in our GCSE course library, at Foundation tier. There are 3 teaching sections and 2 fully worked examples, plus 3 sets of check questions. It sits alongside Percentage Change, Proportion Graphs, Ratio and Ratio & Algebra in the same strand. Endless extra practice on this strand is available on the Ratio and Proportion revision engine, which generates a fresh question each time.
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