In the following number series a wrong number is given.

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In the following number series a wrong number is given. Find out that number. 8, 18, 40, 86, 178, 370, 752

1. 178
2. 180
3. 128
4. 156

Correct Option: A

The pattern is :
8 × 2 + 2 = 16 + 2 = 18
18 × 2 + 4 = 36 + 4 = 40
40 × 2 + 6 = 80 + 6 = 86
86 × 2 + 8 = 172 + 8 = 180 ≠ 178
Since , 178 is wrong term . so , 180 is correct term .
Thus , required answer is 178.
180 × 2 + 10 = 360 + 10 = 370