What should come in place of question mark (?) in the given number series ?
5 12 23 43 79 ?

Options

A. 130
B. 110
C. 140
D. 160

Answer

To solve the problem of finding the missing number in the series 5, 12, 23, 43, 79, ?, we will analyze the differences between consecutive terms and identify a pattern.

### Step-by-Step Solution:

1. **Identify the Series**:
The given series is: 5, 12, 23, 43, 79, ?

2. **Calculate the First Differences**:
We find the differences between consecutive terms:
- 12 - 5 = 7
- 23 - 12 = 11
- 43 - 23 = 20
- 79 - 43 = 36

So, the first differences are: 7, 11, 20, 36.

3. **Calculate the Second Differences**:
Now, we calculate the differences of the first differences:
- 11 - 7 = 4
- 20 - 11 = 9
- 36 - 20 = 16

So, the second differences are: 4, 9, 16.

4. **Identify the Pattern in Second Differences**:
The second differences (4, 9, 16) are perfect squares:
- 4 = 2²
- 9 = 3²
- 16 = 4²

This suggests that the next second difference should be 5² = 25.

5. **Calculate the Next First Difference**:
We add the next second difference (25) to the last first difference (36):
- 36 + 25 = 61

So, the next first difference is 61.

6. **Calculate the Next Term in the Series**:
Finally, we add this new first difference (61) to the last term in the original series (79):
- 79 + 61 = 140

Therefore, the missing number in the series is 140.

### Conclusion:
The number that should come in place of the question mark (?) is **140**.