1. Repeated Percentage Change – Increase & Decrease – Demonstration
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2. n Repeated Percentage Change 1st Year = 350 × 1.1 2nd Year =
John deposited $350 in a bank.
He earned 10% compound interest every year.
How much was in the account after 4 years?
1st Year =
350 × 1.1
Multiplier:
= 100% + 10% =
= 1.1
2nd Year =
(350 × 1.1) × 1.1
3rd Year =
((350 × 1.1) × 1.1) × 1.1
4th Year =
(((350 × 1.1) × 1.1) × 1.1) × 1.1
= $512.44 n
SIMPLIFY
nth Year =
350 × 1.1
Formula:
Quantity × Multiplier
Years

3. n Repeated Percentage Change 1st Year = 220 × 0.85 2nd Year =
Sally invested £220 in a company.
She lost 15% every year!
How much was her investment worth after 3 years?
Multiplier:
= 100% − 15%
= 1.0 − 0.15
= 0.85
1st Year =
220 × 0.85
2nd Year =
(220 × 0.85) × 0.85
3rd Year =
((220 × 0.85) × 0.85) × 0.85
= £135.11 n
SIMPLIFY
nth Year =
220 × 0.85
Formula:
Quantity × Multiplier
Years

4. 160 × 1.23 = £276.48 Repeated Percentage Change Formula:
Quantity × Multiplier
Years
Abi deposited £160 in a bank.
She earned
20% compound interest every year.
How much was in the account after 3 years?
Multiplier:
= 100% + 20% =
= 1.2
160 × 1.23 =
£276.48

5. 230 × 1.074 = £301.48 Repeated Percentage Change Formula:
Quantity × Multiplier
Years
Mark deposited £230 in a bank.
He earned
7% compound interest every year.
How much was in the account after 4 years?
Multiplier:
= 100% + 7% =
= 1.07
230 × =
£301.48

6. 250 × 1.0355 = £296.92 Repeated Percentage Change Formula:
Quantity × Multiplier
Years
Anna deposited £250 in a bank.
She earned
3.5% compound interest every year.
How much was in the account after 5 years?
Multiplier:
= 100% + 3.5% =
= 1.035
250 × =
£296.92

7. 180 × 0.895 = £100.51 Repeated Percentage Change Formula:
Quantity × Multiplier
Years
Marge invested £180 in a company.
She lost 11% every year!
How much was the
investment worth after 5 years?
Multiplier:
= 100% − 11%
= 1.0 − 0.11
= 0.89
180 × =
£100.51

8. 220 × 0.973 = £200.79 Repeated Percentage Change Formula:
Quantity × Multiplier
Years
Tony invested £220 in a company.
He lost 3% every year!
How much was the
investment worth after 3 years?
Multiplier:
= 100% − 3%
= 1.0 − 0.03
= 0.97
220 × =
£200.79

9. 90 × 0.9553 = £78.39 Repeated Percentage Change Formula:
Quantity × Multiplier
Years
Max invested £90 in a company.
He lost 4.5% every year!
How much was the
investment worth after 3 years?
Multiplier:
= 100% − 4.5%
= 1.0 − 0.045
= 0.955
90 × =
£78.39

10. Who finished with the most money?
Repeated Percentage Change
Who finished with the most money?
Formula:
Quantity × Multiplier
Years
Jay earned 15% compound interest
on $360 invested for 4 years.
Mark deposited £230 in a bank.
He earned
7% compound interest every year.
How much was in the account after 4 years?
Hannah earned 6% compound interest
on $420 invested for 3 years.
Sab lost 13% per year
on $800 invested for 5 years.
Multiplier:
= 100% + 7% =
= 1.07
Minnie lost 8% per year
on $860 invested for 3 years.
Did Olaf do even better?
230 × =
£301.48
Olaf earned 6.8% compound interest
on $600 invested for 4 years,
but then lost 5.4% per year for 2 years!

11. Who finished with the most money?
Repeated Percentage Change
Who finished with the most money?
Jay earned 15% compound interest
on $360 invested for 4 years.
Jay = $629.64
Hannah earned 6% compound interest
on $420 invested for 3 years.
Hannah = $500.23
Sab lost 13% per year
on $800 invested for 5 years.
Sab = $398.74
Minnie lost 8% per year
on $860 invested for 3 years.
Minnie = $669.67
Did Olaf do even better?
Olaf earned 6.8% compound interest
on $600 invested for 4 years,
but then lost 5.4% per year for 2 years!
Olaf = $698.58

12. tom@goteachmaths.co.uk Questions? Comments? Suggestions?
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