Percentage Change in Trading
This topic covers 4 learning steps, guiding your child from the basics through to confident problem-solving. Each step includes a worked example and adaptive practice questions.
What Your Child Will Learn
- Calculate Percentage Change
Find percentage increase or decrease between values - Percentage Profit & Loss
Express trading profit/loss as a percentage - Repeated Percentage Change
Apply percentage changes over multiple periods - Challenge — Trading Portfolio Problems
Complex multi-step percentage change scenarios
Before This Topic
Your child should be comfortable with:
- Complex Percentage Trading (Year 6)
- Negative Numbers (Year 6)
Common Mistakes
- Calculating percentage change by just subtracting the two values (e.g. "It went from £40 to £50, so that is 10%")
Percentage change = (change ÷ original) × 100. Going from £40 to £50 is a £10 change, and £10 ÷ £40 × 100 = 25% increase, not 10%. - Thinking a 50% increase followed by a 50% decrease gets you back to the start
It does not. If £100 increases by 50% it becomes £150. Then a 50% decrease on £150 is £75, not £100. The percentage is calculated on a DIFFERENT amount each time.
Tips for Parents
- Use pocket money or savings: "You had £20 last month and £25 this month. What percentage increase is that?" Work through the formula together: (5 ÷ 20) × 100 = 25%.
- Discuss real trading scenarios: "You bought a game for £15 and sold it for £18. What was your percentage profit?" (3 ÷ 15) × 100 = 20% profit.
- Show that percentage changes are not symmetrical: a 20% rise then a 20% fall does NOT return to the original. Try it with £100 → £120 → £96.
- For repeated changes, use multipliers: two successive 10% increases = 1.1 × 1.1 = 1.21, which is a 21% total increase, not 20%.
Key Words
- Percentage change — How much something has gone up or down expressed as a percentage of the original — calculated as (change ÷ original) × 100.
- Profit — The money gained when you sell something for more than you paid — buy for £10, sell for £15, profit is £5.
- Loss — The money lost when you sell something for less than you paid — buy for £10, sell for £7, loss is £3.
- Repeated percentage change — Applying a percentage change more than once — like interest being added year after year.
- Multiplier — The decimal that represents a percentage change — a 15% increase uses a multiplier of 1.15.
Where This Fits
Before this topic: Children should be able to find percentages of amounts and understand percentage increases and decreases as single operations.
After this topic: Percentage change leads to compound interest, depreciation, growth and decay problems, and financial literacy topics in GCSE maths.
How MathCraft Teaches This
In MathCraft, Percentage Change in Trading is taught through the Money, Data & Measure adventure track. Your child follows guided lessons with friendly characters, works through examples step by step, then practises with questions that adapt to their level.
The adaptive engine tracks mastery across all 4 steps, revisiting concepts your child finds tricky and advancing when they're ready. Parents can see detailed progress in the Parent Dashboard.
Practise Percentage Change in Trading with MathCraft
Step-by-step lessons, worked examples, and adaptive practice — all wrapped in an adventure game your child will love.
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