What should come in place of question mark (?) in the following number series?
2 5 17 71 359 ?

Options

A. 1795
B. 2159
C. 1699
D. 1831

Answer

To solve the number series: 2, 5, 17, 71, 359, ?, we need to identify the pattern in the series.

### Step-by-step Solution:

1. **Identify the first transition**:
- From 2 to 5:
- \( 2 \times 2 + 1 = 5 \)

2. **Identify the second transition**:
- From 5 to 17:
- \( 5 \times 3 + 2 = 17 \)

3. **Identify the third transition**:
- From 17 to 71:
- \( 17 \times 4 + 3 = 71 \)

4. **Identify the fourth transition**:
- From 71 to 359:
- \( 71 \times 5 + 4 = 359 \)

5. **Identify the fifth transition**:
- Now, we need to find the next number after 359:
- We will multiply 359 by 6 and then add 5.
- Calculation:
- \( 359 \times 6 = 2154 \)
- \( 2154 + 5 = 2159 \)

Thus, the number that should come in place of the question mark (?) is **2159**.

### Final Answer:
2159