GCSE number
Percentage change without common mistakes
Use this guide as a revision starting point, then practise with questions matched to your course and exam board.
Percentage change compares the amount of change with the original value, not the final value.
Core formula
percentage change = change ÷ original × 100A price rises from £80 to £92. The change is £12. Therefore, 12 ÷ 80 × 100 = 15%.
Multiplier method
For a 15% increase, multiply by 1.15. For a 15% decrease, multiply by 0.85.
Common check
Always identify the original value before calculating the percentage.