Simple interest

The Maths Habit

The bank adds the same pile of coins every year. Who gets more coins?

AmyYear 1Year 2Year 3Year 412 coins ✓ moreBenYear 1Year 210 coins

Work out 10% of each amount.

10% of £60£6
10% of £90£9
10% of £200£20

Interest
Extra money paid on money that is saved or borrowed.
Simple interest
The same interest every year.
Year 1Year 2Year 3
Rate
The percentage paid each year.
10% a year

£40 is saved at 10% simple interest a year. Find the interest for 3 years.

1Find one year's interest.
10% =£40÷10=£4
2Write it in every year.
Year 1£4Year 2£4Year 3£4
3Multiply by the years.
3 years =£4×3=£12

£70 is saved at 10% simple interest a year. Find the interest for 2 years.

1Find one year's interest.
10% =£70÷10=£7
2Write it in every year.
Year 1£7Year 2£7
3Multiply by the years.
2 years =£7×2=£14

£40 is saved at 10% simple interest a year. Find the interest for 3 years.

1Find one year's interest.
10% =£40÷10=£4
2Write it in every year.
Year 1£4Year 2£4Year 3£4
3Multiply by the years.
3 years =£4×3=£12
110% =amount÷10=10%2Year 1sameYear 2sameYear 3same3one year×years=interest

£30 is saved at 10% simple interest a year. Find the interest for 5 years.

1Find one year's interest.
10% =£30÷10=£3
2Write it in every year.
Year 1£3Year 2£3Year 3£3Year 4£3Year 5£3
3Multiply by the years.
5 years =£3×5=£15

£40 is saved at 10% simple interest a year. Find the interest for 3 years.

1Find one year's interest.
10% =£40÷10=£4
2Write it in every year.
Year 1£4Year 2£4Year 3£4
3Multiply by the years.
3 years =£4×3=£12
110% =amount÷10=10%2Year 1sameYear 2sameYear 3same3one year×years=interest

£50 is saved at 10% simple interest a year. Find the interest for 2 years.

1Find one year's interest.
10% =£50÷10=£5
2Write it in every year.
Year 1£5Year 2£5
3Multiply by the years.
2 years =£5×2=£10

£40 is saved at 10% simple interest a year. Find the interest for 3 years.

1Find one year's interest.
10% =£40÷10=£4
2Write it in every year.
Year 1£4Year 2£4Year 3£4
3Multiply by the years.
3 years =£4×3=£12
110% =amount÷10=10%2Year 1sameYear 2sameYear 3same3one year×years=interest

Raj saves £80 in a bank. It pays 10% simple interest a year. How much interest does he get in 3 years?

1Find one year's interest.
10% =£80÷10=£8
2Write it in every year.
Year 1£8Year 2£8Year 3£8
3Multiply by the years.
3 years =£8×3=£24

5% is half of 10%. Find 5%.

10% is £85% is £4
10% is £65% is £3
10% is £105% is £5

£40 is saved at 5% simple interest a year. Find the interest for 3 years.

1Find one year's interest.
10% =£40÷10=£4
5% =£4÷2=£2
2Write it in every year.
Year 1£2Year 2£2Year 3£2
3Multiply by the years.
3 years =£2×3=£6

£100 is saved at 5% simple interest a year. Find the interest for 2 years.

1Find one year's interest.
10% =£100÷10=£10
5% =£10÷2=£5
2Write it in every year.
Year 1£5Year 2£5
3Multiply by the years.
2 years =£5×2=£10

£40 is saved at 5% simple interest a year. Find the interest for 3 years.

1Find one year's interest.
10% =£40÷10=£4
5% =£4÷2=£2
2Write it in every year.
Year 1£2Year 2£2Year 3£2
3Multiply by the years.
3 years =£2×3=£6
110% =amount÷10=10%5% =10%÷2=5%2Year 1sameYear 2sameYear 3same3one year×years=interest

£20 is saved at 5% simple interest a year. Find the interest for 4 years.

1Find one year's interest.
10% =£20÷10=£2
5% =£2÷2=£1
2Write it in every year.
Year 1£1Year 2£1Year 3£1Year 4£1
3Multiply by the years.
4 years =£1×4=£4

£40 is saved at 5% simple interest a year. Find the interest for 3 years.

1Find one year's interest.
10% =£40÷10=£4
5% =£4÷2=£2
2Write it in every year.
Year 1£2Year 2£2Year 3£2
3Multiply by the years.
3 years =£2×3=£6
110% =amount÷10=10%5% =10%÷2=5%2Year 1sameYear 2sameYear 3same3one year×years=interest

£80 is saved at 5% simple interest a year. Find the interest for 5 years.

1Find one year's interest.
10% =£80÷10=£8
5% =£8÷2=£4
2Write it in every year.
Year 1£4Year 2£4Year 3£4Year 4£4Year 5£4
3Multiply by the years.
5 years =£4×5=£20

£40 is saved at 5% simple interest a year. Find the interest for 3 years.

1Find one year's interest.
10% =£40÷10=£4
5% =£4÷2=£2
2Write it in every year.
Year 1£2Year 2£2Year 3£2
3Multiply by the years.
3 years =£2×3=£6
110% =amount÷10=10%5% =10%÷2=5%2Year 1sameYear 2sameYear 3same3one year×years=interest

Ella borrows £60. She pays 5% simple interest a year. How much interest does she pay in 4 years?

1Find one year's interest.
10% =£60÷10=£6
5% =£6÷2=£3
2Write it in every year.
Year 1£3Year 2£3Year 3£3Year 4£3
3Multiply by the years.
4 years =£3×4=£12

Simple interest worksheet, page 1

Simple interest worksheet, page 2

Answer sheet

Simple interest. Is it right?
Thumbs up: right. Thumbs down: wrong.

  1. £50 at 10% for 3 years: interest £15

    Right

  2. £40 at 10% for 2 years: interest £4

    Wrong: one year

  3. £80 at 5% for 2 years: interest £8

    Right

  4. £60 at 5% for 3 years: interest £18

    Wrong: used 10%

  5. £100 at 10% for 4 years: interest £40

    Right

  1. £200 is saved at 10% simple interest a year for 3 years. How much is it worth at the end?

    £260

  2. £300 is saved at 2% simple interest a year. Find the interest for 4 years. Hint: 1% is £3.

    £24

  3. £500 earns £100 simple interest in 4 years. What is the rate?

    5% (£25 a year)

  1. £50 is saved at 10% simple interest a year. Find the interest for 3 years.

    £15
    10% =£50÷10=£51Year 1£5Year 2Year 323 years =×=3

  2. £40 is saved at 5% simple interest a year. Find the interest for 5 years.

    £10
    10% =÷10=5% =÷2=1Year 1Year 2Year 3Year 4Year 525 years =×=3

  3. £80 is saved at 5% simple interest a year. Find the interest for 4 years.

    £16
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