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This topic covers repeated proportional growth and decay over time using multipliers to a power, applied to interest, depreciation and populations. It's a core topic in GCSE and iGCSE Maths with Edexcel and the other major boards. This free interactive course teaches the method with worked examples and gives instant-feedback practice questions to lock it in.
How you do it
Find the multiplier for one step, then raise it to the power of the number of steps. Growth gives a multiplier above 1, decay below it. To find how many steps to reach a target, use trial and improvement or logarithms at A-Level.
Before you start
You will want percentage multipliers and indices at your fingertips first. It underpins exponential models at A-Level.
What you learn
The compound multiplier isn’t just for money. Populations grow, medicines clear from the blood, and radioactive material decays — all by the same percentage each period. Decay uses a multiplier below 1, applied once per period. Sometimes you know the target and need the number of periods. The course works through compound growth, compound decay in context and finding the number of periods. 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
Compound Growth & Decay is a Number topic in the GCSE syllabus, covered here at Higher tier. It runs to 3 concepts, each followed by a check, with 2 worked examples along the way. Students often pair it with Compound Interest & Decay, Error Intervals, FDP Equivalence, Four Operations and Fractional & Negative Indices. The Number revision engine gives you as many extra questions as you want, tracked on your skill tree.
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