Starter quiz
- Increase 65 by 5%
- '68.25' ✓
- Decrease 60 by 5%
- '57' ✓
- If a number increases by 70% and is now 85, what was it originally?
- '50' ✓
- Decrease 250 by 15%
- '212.5' ✓
- A mathematician celebrates their shares increasing by 12% which are now worth £100.80. How much did they originally invest?
- '£90' ✓
- If a number increases by 82% and is now 163.8, what was it originally?
- '90' ✓
Exit quiz
- If I increase £45 to £54, what is the percentage gain?
- '20' ✓
- If I increase £45 to £99, what is the percentage gain?
- '120' ✓
- If I increase £14 to £56, what is the percentage gain?
- '300' ✓
- If I decrease £90 to £18, what is the percentage loss?
- '80%' ✓
- If I decrease £88 to £66, what is the percentage loss?
- '25' ✓
- Match the following so that the number on the right reflects a 20% percentage loss on the number on the left.
- £500⇔£400 ✓
- £530⇔£424 ✓
- £700⇔£560 ✓
- £592⇔£473.60 ✓
Worksheet
Loading worksheet ...
Presentation
Loading presentation ...
Video
Lesson Details
Key learning points
- When calculating percentage profit or loss, you are interested in the change.
- If the final amount is more than the original, there is profit.
- If the final amount is less than the original, there is loss.
- This change can be described as a percentage of the original amount.
- A negative percentage is interpreted as a loss.
Common misconception
When using multipliers, pupils can mistake a decimal for the percentage decrease. e.g. 0.52 is a 52% decrease, rather than recognising a 48% decrease
Reminding students that a decimal multiplier greater than 1 means an increase, and a decimal multiplier less than 1 means a decrease. The latter requires a subtraction from 1 or 100%
Keywords
Percentage profit - is the increase when referencing something that is sold for more than the cost price given as a percentage of the original amount
Percentage loss - is the decrease when referencing something that is sold for less than the cost price given as a percentage of the original amount
+