Percentage increase and decrease
Put a price or a wage up or down by a percentage, and work out the percentage change between an old figure and a new one.
In this room: 3 tasks, 10 questions
- Changing an amount by a percentage4 questions
- Finding the percentage change4 questions
- A rise and a cut do not cancel out2 questions
A price rise or a pay rise is often given as a percentage. So is a price cut.
- Step 1: work out the percentage of the amount
- Step 2: add it for an increase, or take it away for a decrease
Worked example: a drill costs £80 and goes up by 5%. 5% of £80 is £4. The new price is £80 + £4 = £84.
Answer the questions below
3 more questions follow in this task.
Here you know the old figure and the new figure, and want the change as a percentage.
- Step 1: find the change, which is the gap between the new figure and the old one
- Step 2: divide the change by the old figure
- Step 3: multiply by 100
Worked example: a tin of paint goes from £20 to £25. The change is £5. 5 ÷ 20 = 0.25, and × 100 gives an increase of 25%.
Always divide by the old figure, never the new one.
Answer the questions below
3 more questions follow in this task.
A percentage is always taken from the amount in front of it. After a rise, that amount is bigger.
Worked example: £80 goes up by 50% to £120. A cut of 50% then takes off half of £120, which leaves £60, not £80.
Answer the questions below
1 more question follows in this task.