Compound Interest
Compound interest builds on percentage multiplier methods to model growth and decay over time. Students apply repeated percentage change to financial contexts, population growth, and depreciation problems.
Tier
Exam Board
No questions match the current filters for Compound Interest.
What You'll Learn
- Calculating compound interest using repeated multipliers
- Finding the value after depreciation
- Determining the number of years to reach a target amount
- Comparing simple and compound interest
Watch Out For These Mistakes
Students make these errors again and again. Knowing them in advance gives you a head start.
Using simple interest calculations instead of compound (multiplying by n instead of raising to the power n)
Forgetting that a 3% increase uses a multiplier of 1.03, not 0.03
Not reading whether the question asks for the total amount or just the interest earned
What Examiners Say About Compound Interest
Insights pulled from Cambridge IGCSE (0580) examiner reports — the exact mistakes candidates make every year.
- Common Mistake●●●●●
For train-crossing-bridge problems: (1) Total distance = train length + bridge length, (2) Convert all units to be consistent (all metres + seconds, or all km + hours) BEFORE calculating.
Source: CIE 0580 · Feb/March 2024 · Paper 2 · Q14
- Common Mistake●●●●●
If 5/13 are sold, then 8/13 remain. Set the remainder (96) equal to the remaining fraction (8/13 of total), not the sold fraction. A decimal answer in a whole-number context should alert you to an err
Source: CIE 0580 · Feb/March 2021 · Paper 1 · Q13
- Misconception●●●●●
Percentage profit = (profit / COST PRICE) × 100 — divide by COST, not selling price. Profit = selling − cost. This is the most-missed type of percentage question.
Source: CIE 0580 · May/June 2021 · Paper 3 · Q1f(i)
Based on 3of 500+ insights extracted from CIE 0580 examiner reports (2018–2024).
Exam Coverage
This topic appears in the Cambridge IGCSE past papers. Our AI tutor can help with it on any question.
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Ratio, proportion, and percentage formulae