1. Simple Interest Success Criteria Learning Intention
1. To introduce the terms Interest, Rate, pa and Deposit.
1. To be able to understand terms Interest, rate pa and Deposit
2. To show how to calculate the simple interest for 1 year
2. Can calculate Simple Interest for 1 year.
3. To show how to calculate the amount after interest is paid
3. Can calculate Simple Interest for part of a year
4. To show how to calculate the interest for part of a year

2. What is Interest
If you DEPOSIT money in a bank account then the bank will pay you a percentage as INTEREST
The RATE of interest is given as a percentage per annum
per annum is another phrase for per year
John DEPOSITS £200
£200
SCOTIA BANK
rate of interest
3.2% p.a.
Interest ( 1 yr ) = of
Jill DEPOSITS £600
£600
3.2%
3.2%
Interest ( 1 yr ) = of

3. How to Calculate Interest ( 1)
The 1st step in all Simple Interest questions is to calculate the Interest due for 1 year ( annum )
Find the Interest a bank will pay on a Principal of £400 when the Interest rate is 7.5% p.a.
Interest ( 1 Year ) =
7.5% of £400 of
400
400
7.5
= 7.5
÷ 100 % x
= £30

4. How to Calculate Interest ( 2)
The 1st step in all Simple Interest questions is to calculate the Interest due for 1 year ( annum )
Find the Interest a bank will pay on a Principal of £400 when the Interest rate is 7.5% p.a.
Interest ( 1 Year ) =
7.5% of £400
7.5 x
400 =
100 =
400
÷ 100
x 7.5
= £30
7.5% is
7.5
out of
100

5. Calculating Interest for 1 year
£730 at Rate of 2% p.a. = =
(b)
£290 at Rate of 4% p.a. = =
(c)
£1000 at Rate of 3.5% p.a. = =
(d)
£300 at Rate of 5% p.a. = =
(e)
£880 at Rate of 7% p.a. = =
(f)
£140 at Rate of 8% p.a. = =
(g)
£470 at Rate of 10.5% p.a. = =
(-) √ C x ÷
Show Ans C 5 6 7 8 9 + - On 1 2 3 4 . =
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Ans

6. Amount in Bank after Interest
Banks automatically add interest to your bank account
AMOUNT = What you had in bank ( Principal ) + Interest
Rate of Interest
10.5%
p.a.
Money in Bank
£600
Interest(1 yr) = =
10.5 =
600
Amount = =
2.1
Original +
Interest of
(-) √ C x ÷
Setup 5 6 7 8 9 + - On
Next 1 2 3 4 . =
Ans

7. Amount = Principal + Interest
£140 at Rate of 10.5% p.a. = =
(b)
£920 at Rate of 8.9% p.a. = =
(c)
£1050 at Rate of 3% p.a. = =
(d)
£720 at Rate of 7.3% p.a. = =
(e)
£450 at Rate of 9.5% p.a. = =
(f)
£800 at Rate of 4% p.a. = =
(g)
£560 at Rate of 1% p.a. = =
Show Ans C
(-) √ C x ÷ 5 6 7 8 9 + - On 1 2 3 4 . =
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Ans

8. Interest : Part of a year
Half of the interest due for 1 year
Karen deposited £2000 in her bank account in April.
The bank pays a rate of 4% Interest per annum
6 months later she decided to buy a car and asked the bank teller how much interest she would get
Interest for 1 year = 4% of £2000=
£80
Interest for 6 month =
£80 ÷ 2 = £40
Total in Bank =
£ £40 = £2040 6
part
4 ÷ 100 x 2000 80
Part of ….. Fraction of …. 12
total 6 12
= 6 ÷ 12 = 0.5 = a half

9. Part of a year 4 970 Setup Any Month of . Rate of Interest 4% months
Deposit
£970
for 4 =
Interest(1 yr) = =
As the money is left in for less than a year the Interest paid will be a fraction of that paid for 1 year
part 4
Interest 4
months = x
970
Setup
total
Any Month = = of
6 Months
(-) √ C x ÷
3 Months 5 6 7 8 9 + - On
4 Months 1 2 3 4 . =
Ans

10. Interest : Part of a Year
Interest due
(a)
On £1320 at 7% for 6 month = =
(b)
On £2400 at 10.4% for 3 month = =
(c)
On £3600 at 3% for 4 month = =
(d)
On £10320 at 8% for 9 month = =
(e)
On £7440 at 6% for 2 month = =
(f)
On £4200 at 9.1% for 1 month = =
(g)
On £8520 at 4.5% for 8 month = =
Show Ans C
(-) √ C x ÷
3, 4 or 6
Months 5 6 7 8 9 + - On 1 2 3 4 . =
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Ans

11. Test . . C √ ² 7 8 9 x (-) √ ² C x ÷ 4 5 6 ÷ 5 6 7 8 9 + - 1 2 3 - 1 2
(-)
Ans On C √ 7 8 9 x
(-) √ C x ÷
Test 4 5 6 ÷ 5 6 7 8 9 + - On 1 2 3 - 1 2 3 4 . =
Ans . = +

12. (a)
r = 16 ; s = 65 V= =
(b)
r = 7 ; s = 25 V= =
(c)
r = 18 ; s = 82 V= =
(d) V=
r = 10 ; s = 26 = V=
(e)
r = 12 ; s = 37 =
(f)
r = 11 ; s = 61 V= =
(g)
r = 13 ; s = 85 V= =
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