18

72

18

72

18÷2

72÷2

9

36

9÷3

36÷3

3

12

3÷3

12÷3

1

4

or

18

72

2 × 3 × 3

2 × 2 × 2 × 3 × 3

1

4

or

Common Divisors for 18 and 72 are: 2, 3 and 3

Greatest Common Divisor = 2 × 3 × 3 = 18

18÷18

72÷18

1

4

See 1/4 as a percent