Simplifying ratios

The Maths Habit

Which glass of squash is stronger?

Glass A

Glass B

They are the same strength

What is the highest common factor?

12 and 20 4

Simplest form
A ratio is in its simplest form when its numbers cannot be divided any further.
Highest common factor
The biggest number that divides exactly into both numbers.

8:12 2:3

16 : 40

36 : 60

12 : 20

123 groups205 groups
HCF of 12 and 20 is 4
÷ 43:÷ 45
Answer3 : 5

14 : 35

142 groups355 groups
HCF of 14 and 35 is 7
÷ 72:÷ 75
Answer2 : 5

12 : 20

123 groups205 groups
HCF of 12 and 20 is 4
÷ 43:÷ 45
Answer3 : 5

24 : 32

243 groups324 groups
HCF of 24 and 32 is 8
÷ 83:÷ 84
Answer3 : 4

12 : 20

123 groups205 groups
HCF of 12 and 20 is 4
÷ 43:÷ 45
Answer3 : 5

18 : 27

182 groups273 groups
HCF of 18 and 27 is 9
÷ 92:÷ 93
Answer2 : 3

12 : 20

123 groups205 groups
HCF of 12 and 20 is 4
÷ 43:÷ 45
Answer3 : 5

30 : 12

305 groups122 groups
HCF of 30 and 12 is 6
÷ 65:÷ 62
Answer5 : 2

12 : 20

123 groups205 groups
HCF of 12 and 20 is 4
÷ 43:÷ 45
Answer3 : 5

6 : 21

62 groups217 groups
HCF of 6 and 21 is 3
÷ 32:÷ 37
Answer2 : 7

Simplifying ratios worksheet, page 1

Simplifying ratios worksheet, page 2

Answer sheet

  1. Write 20 minutes : 1 hour as a ratio in its simplest form.

    1 : 3

  2. Write 12 : 18 : 30 in its simplest form.

    2 : 3 : 5

  3. A ratio simplifies to 3 : 4. Its first number was 21. What was its second number?

    28

  1. Write 24 : 36 in its simplest form.

    2 : 3

  2. Write 40 cm : 2 m in its simplest form.

    1 : 5

  3. Ola writes 36 : 48 as 6 : 8. Is that in its simplest form? Explain.

    No: 3 : 4, the HCF is 12
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