What will come in place of the question mark (?) in the following number series?
`3" "6" "21" "28" "55" "66" "?" "120`

Options

A. 103
B. 104
C. 108
D. 105

Answer

To solve the number series `3, 6, 21, 28, 55, 66, ?, 120`, we need to identify the pattern in the series.

### Step-by-Step Solution:

1. **Identify the series**: The series is `3, 6, 21, 28, 55, 66, ?, 120`.

2. **Look for patterns**:
- The first two numbers are `3` and `6`.
- Notice that `6` is `2 * 3`.
- The next number is `21`, which can be expressed as `7 * 3`.
- The number after that is `28`, which can be expressed as `4 * 7`.

3. **Continue analyzing**:
- The next two numbers are `55` and `66`.
- `55` can be expressed as `5 * 11` and `66` can be expressed as `6 * 11`.

4. **Establish the pattern**:
- The first two numbers are multiples of `3` (1 and 2 times `3`).
- The next two numbers are multiples of `7` (3 and 4 times `7`).
- The last two numbers are multiples of `11` (5 and 6 times `11`).

5. **Predict the next numbers**:
- Following the established pattern, the next two numbers should be multiples of `15` (7 and 8 times `15`).
- The 7th term (the one we need to find) will be `7 * 15 = 105`.
- The 8th term is `8 * 15 = 120`, which is already given.

6. **Conclusion**:
- Therefore, the number that will come in place of the question mark (?) is `105`.

### Final Answer:
The answer is `105`.

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