12 35 81 173 357 (?)

Options

A. 725
B. 715
C. 726
D. 736

Explanation

To find the missing number in the series: 12, 35, 81, 173, 357, (?), we can follow these steps:

### Step 1: Identify the pattern
We observe that each term in the series seems to be generated by a specific operation involving the previous term. Let's analyze the transitions between the numbers.

### Step 2: Calculate the operations
1. From 12 to 35:
- \( 12 \times 2 + 11 = 24 + 11 = 35 \)

2. From 35 to 81:
- \( 35 \times 2 + 11 = 70 + 11 = 81 \)

3. From 81 to 173:
- \( 81 \times 2 + 11 = 162 + 11 = 173 \)

4. From 173 to 357:
- \( 173 \times 2 + 11 = 346 + 11 = 357 \)

### Step 3: Apply the same operation for the next term
Now, we will apply the same operation to find the next term after 357:
- \( 357 \times 2 + 11 = 714 + 11 = 725 \)

### Conclusion
The missing number in the series is **725**.

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