Which of the following numbers is divisible by 9?

1. 972063

2. 730542

3. 785423

4. 5612844

A number is divisible by 9 if the sum of its digits is divisible by 9.

1. 972063: sum = 9 + 7 + 2 + 0 + 6 + 3 = 27, divisible by 9. ✓

2. 730542: sum = 7 + 3 + 0 + 5 + 4 + 2 = 21, not divisible by 9.

3. 785423: sum = 7 + 8 + 5 + 4 + 2 + 3 = 29, not divisible by 9.

4. 5612844: sum = 5 + 6 + 1 + 2 + 8 + 4 + 4 = 30, not divisible by 9.

Hence, option 1 is the correct option.