What should come is place of the question mark (?) in the following number series ?
`5" " 54" "90" "115" "131" "140" "?`

Options

A. 149
B. 144
C. 142
D. 152

Answer

To find the missing number in the series `5, 54, 90, 115, 131, 140, ?`, we will analyze the differences between consecutive terms.

### Step-by-Step Solution:

1. **List the numbers in the series:**
\[ 5, 54, 90, 115, 131, 140, ? \]

2. **Calculate the differences between consecutive terms:**
- Difference between 54 and 5:
\[ 54 - 5 = 49 \]
- Difference between 90 and 54:
\[ 90 - 54 = 36 \]
- Difference between 115 and 90:
\[ 115 - 90 = 25 \]
- Difference between 131 and 115:
\[ 131 - 115 = 16 \]
- Difference between 140 and 131:
\[ 140 - 131 = 9 \]

So, the differences are:
\[ 49, 36, 25, 16, 9 \]

3. **Identify the pattern in the differences:**
The differences are:
\[ 7^2, 6^2, 5^2, 4^2, 3^2 \]
This indicates that the next difference should be:
\[ 2^2 = 4 \]

4. **Calculate the next term using the identified pattern:**
- The last term we have is 140. To find the next term, we add the next difference (4):
\[ 140 + 4 = 144 \]

5. **Conclusion:**
The missing number in the series is:
\[ \boxed{144} \]