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Reverse percentages — 'finding the original amount' — work back from a value after a percentage change to the original, such as the pre-sale price or the amount before VAT. Students often confuse this with ordinary percentage change. It's examined right across GCSE and iGCSE Maths. Learn it free on eClassroom through guided worked examples and instantly-marked exam-style questions.
How you do it
The amount you are given is not 100 percent, so you cannot just take the percentage off. Work out what percentage the amount represents, then divide by that decimal multiplier to get back to the original.
Before you start
Before starting, revisit percentages and forming equations. Keep it sharp for compound interest and depreciation problems.
What you learn
Reverse percentages find the original amount before a change — the price before the sale, the bill before VAT. The trick is to work backwards with a multiplier. A percentage change multiplies the original, so to undo it you divide by the same multiplier. The course works through working backwards, original after a decrease and spotting reverse percentage problems. 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
Reverse Percentages is part of the Number strand of our free GCSE maths courses, studied in Foundation tier. There are 3 teaching sections and 2 fully worked examples, plus 3 sets of check questions. It sits alongside Rounding & Estimation, Significant Figures & Truncation, Standard Form and Standard Units & Measures in the same strand. Endless extra practice on this strand is available on the Number revision engine, which generates a fresh question each time.
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