90

72

90

72

72

72

18

72

18

72

1

18

72

1

18÷2

72÷2

1

9

36

1

9÷3

36÷3

1

3

12

1

3÷3

12÷3

1

1

4

or

90

72

72

72

18

72

18

72

1

18

72

1

18

72

1

2 × 3 × 3

2 × 2 × 2 × 3 × 3

1

1

1

4

or

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

Greatest Common Divisor = 2 × 3 × 3 = 18

1

90÷18

72÷18

1

1

4