1. Multipliers Recap
Work out the multiplier needed to increase an amount by:
1(a) 30%
2(a) 50%
3(a) 70%
1(b) 35%
2(b) 55%
3(b) 7%
1(c) 3%
2(c) 5%
3(c) 7.5%
1(d) 3.5%
2(d) 500%
3(d) 0.7%
Work out the multiplier needed to decrease an amount by:
Starter: in books
4(a) 40%
5(a) 50%
6(a) 60%
4(b) 45%
5(b) 55%
6(b) 6%
4(c) 4%
5(c) 5%
6(c) 6.6%
4(d) 4.5%
5(d) 0.5%
6(d) 0.06%

2. A TV is reduced by 20% in a sale and now costs £240.
How much was the TV before it was reduced? 0%
80%
100%
£60
£60
£60
£60
£60 £0
£240 ?
Allow students to attempt this question first.
Display the common misconception.
Allow students time to discuss, anticipate that many students will still believe this to be true at this point!
We looked at this problem last lesson.

3. We looked at this problem last lesson.
A TV is reduced by 20% in a sale and now costs £240.
How much was the TV before it was reduced? 0%
80%
100%
£60
£60
£60
£60
£60 £0
£240 ?
Allow students to attempt this question first.
Display the common misconception.
Allow students time to discuss, anticipate that many students will still believe this to be true at this point!
We looked at this problem last lesson.
Today we are going to learn a more efficient way of solving problems like this.

4. A TV is reduced by 20% in a sale and now costs £240.
How much was the TV before it was reduced?
To calculate a 20% reduction, we can multiply by 0.8
Allow students to attempt this question first.
Display the common misconception.
Allow students time to discuss, anticipate that many students will still believe this to be true at this point!
Original amount
x 0.8
Sale Price ?
£240
÷𝟎.𝟖

5. A TV is reduced by 20% in a sale and now costs £240.
How much was the TV before it was reduced?
Allow students to attempt this question first.
Display the common misconception.
Allow students time to discuss, anticipate that many students will still believe this to be true at this point!
Original amount
x 0.8
£300
Sale Price
£240
÷𝟎.𝟖

6. On your whiteboards: A bed was reduced by 15% to £357
On your whiteboards: A bed was reduced by 15% to £357. How much did it cost originally?
£420
£357
X 0.85
Original amount
Sale Price

7. On your whiteboards: A lamp was reduced by 22% to £28. 16
On your whiteboards: A lamp was reduced by 22% to £ How much did it cost originally?
£32
£28.16
X 0.88
Original amount
Sale Price

8. On your whiteboards: An investment increased in value by 22% to £6832
On your whiteboards: An investment increased in value by 22% to £ How much was its value initially?
£5600
£6832
X 1.22
Original amount

9. Reverse Percentage Problems
Acknowledgements: MathsPad (more question available from MathsPad

10. Mark/Correct your work

11. Challenge