What should come in place of the question mark '?' in the following number series?

2, 11, 54, 215, 644, ?

- 1280
- 1278
- 1287
- 1295
- None of these

Option 3 : 1287

**Calculation:**

The series follows following pattern:

⇒ 2 × 6 – 1 = 11

⇒ 11 × 5 – 1 = 54

⇒ 54 × 4 – 1 = 215

⇒ 215 × 3 – 1 = 644

⇒ 644 × 2 – 1 = **1287**

**∴ The value of ? is 1287**

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