45

72

45

72

45÷3

72÷3

15

24

15÷3

24÷3

5

8

or

45

72

3 × 3 × 5

2 × 2 × 2 × 3 × 3

2 × 2 × 2 × ~~3~~ × ~~3~~

5

8

or

Common Divisors for 45 and 72 are: 3 and 3

Greatest Common Divisor = 3 × 3 = 9

45÷9

72÷9

5

8

See 5/8 as a percent