72

99

72

99

72÷3

99÷3

24

33

24÷3

33÷3

8

11

or

72

99

2 × 2 × 2 × 3 × 3

3 × 3 × 11

2 × 2 × 2 × ~~3~~ × ~~3~~

8

11

or

Common Divisors for 72 and 99 are: 3 and 3

Greatest Common Divisor = 3 × 3 = 9

72÷9

99÷9

8

11