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

178

The following pattern is observed in the given series: Number x 2+ 2, Resulting number x 2 + (2+2), Resulting number x 2 + (2 + 4)...so on.

8×2+2 =18

18×2+4=40

40×2+6=86

86×2+8=180

It should have been 180, but the series shows 178.

180×2+10=370

370×2+12=752

So, 178 is the wrong number.