What number should replace the question mark?

125, 138, 164, ?, 255

The given series 16, 254, 1296, 4096, 10000 follows a pattern that

24, 44, 64, 84, 104,...

Hence, the odd man in the series is 4 x 4 x 4 x 4 = 256 not 254.

The given number series is 14, 27, 105, 525, 4993

14

14 x 2 - 1 = 27

27 x 4 - 3 = 105

105 x 6 - 5 = 625 (not 525)

625 x 8 - 7 = 4993

Hence, the odd man or number in the given number series is 525.

The given series is 12, 48, 168, 502, 1260

12

12 x 4 = 48

48 x 3.5 = 168

168 x 3 = 504

504 x 2.5 = 1260

Hence, the odd man out in the given series is 502.

Here the given series 222, 271, 308, 332, 348, 357 follows a pattern that

222

222 + 49  271

271 + 36 = 307 (NOT 308)

307 + 25 = 332

332 + 16 = 348

348 + 9 = 357

Hence, the odd man in the fiven number series is 308.

Here the given series 28, 12, 4, 2, -2 follows a pattern that

$$\begin{gathered} 28 \\ 28 - 24 = 28 - 16 = 12 \\ 12 - 23 = 12 - 8 = 4 \\ 4 - 22 = 4 - 4 = 0 (NOT 2) \\ 0 - 21 = 0 - 2 = -2 \end{gathered}$$

Hence, the odd man in the given series is 2.

The given series is 1/2, 1, 3/2, 6, 5/2, 3

1/2

1/2 + 1/2 = 1

1 + 1/2 = 3/2

3/2 + 1/2 = 2 (Not 6)

2 + 1/2 = 5/2

5/2 + 1/2 = 3

Hence, the odd man in the given number series is 6.

Here the given series is 128, 32, 14, 2.66, 0.88

128 / 4 = 32

32 / 3 = 10.666

10.666 / 4 = 2.666

2.666 / 3 = 0.888

Hence, the odd man in the given number series is 14.

The given number series is 720, 732, 708, 742, 696

720

720 + 12 = 732

732 - 24 = 708

708 + 36 = 744 (Not 742)

744 - 48 = 696

Hence, the odd man in the given number series is 742.