To determine which of the given numbers is not divisible by 9, we need to test each option for divisibility by 9. A number is divisible by 9 if the sum of its digits is also divisible by 9. Let's check each number step-by-step:
1. -27
- Sum of digits: 2 + 7 = 9
- 9 is divisible by 9.
- Therefore, -27 is divisible by 9.
2. 72
- Sum of digits: 7 + 2 = 9
- 9 is divisible by 9.
- Therefore, 72 is divisible by 9.
3. 111
- Sum of digits: 1 + 1 + 1 = 3
- 3 is not divisible by 9.
- Therefore, 111 is not divisible by 9.
4. 909
- Sum of digits: 9 + 0 + 9 = 18
- 18 is divisible by 9.
- Therefore, 909 is divisible by 9.
Given this analysis, the number that is not divisible by 9 is:
C) 111
