Percentage change · Grade 7
In Grade 7 you learn: percentage increase and decrease.
Prices, populations and pay change by percentages. A multiplier turns any percentage change into a single multiplication, and working backwards (a reverse percentage) finds the amount before the change.
Key facts
- Increase by r%: multiply by 1 + r/100 (up 15% → × 1.15).
- Decrease by r%: multiply by 1 − r/100 (down 15% → × 0.85).