Find the next number in the given series
9,11, 15, 17, 21, 23 ?

Options

A. 29
B. 28
C. 30
D. 27

Answer

To find the next number in the series 9, 11, 15, 17, 21, 23, we can analyze the differences between consecutive numbers.

1. **Identify the series**: The given series is 9, 11, 15, 17, 21, 23.

2. **Calculate the differences between consecutive terms**:
- 11 - 9 = 2
- 15 - 11 = 4
- 17 - 15 = 2
- 21 - 17 = 4
- 23 - 21 = 2

So, the differences are: 2, 4, 2, 4, 2.

3. **Observe the pattern in the differences**:
- The differences alternate between 2 and 4.
- The pattern is: 2, 4, 2, 4, 2.

4. **Predict the next difference**:
- Following the established pattern, the next difference should be 4 (since the last difference was 2).

5. **Add the next difference to the last term**:
- The last term in the series is 23.
- Therefore, the next term will be: 23 + 4 = 27.

6. **Conclusion**: The next number in the series is 27.

### Final Answer: 27