1 9 25 49 81 ? 169

Options

A. 100
B. 64
C. 81
D. 121

Explanation

To find the missing number in the series: 1, 9, 25, 49, 81, ?, 169, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the given numbers**: The series provided is 1, 9, 25, 49, 81, ?, 169.

2. **Recognize the pattern**: Notice that each number in the series is a perfect square:
- \(1 = 1^2\)
- \(9 = 3^2\)
- \(25 = 5^2\)
- \(49 = 7^2\)
- \(81 = 9^2\)
- The next number should be \(11^2\), which is \(121\).
- Finally, \(169 = 13^2\).

3. **Calculate the missing number**:
- The missing number is \(11^2 = 121\).

4. **Conclusion**: The complete series is 1, 9, 25, 49, 81, 121, 169.

### Final Answer:
The missing number is **121**.

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