What will come in place of the question mark (?) in the following number series?

5, 7, ?, 25, 45, 75

The given number series is 8, 16, 20, 36, 68

8

8 x 2 - 4 = 12 (NOT 16)

12 x 2 - 4 = 20

20 x 2 - 4 = 36

36 x 2 - 4 = 68

Hence, the odd man in the given series is 16.

The given series is 8, 14, 24, 60, 180

8

8 x 1.5 = 12 (NOT 14)

12 x 2 = 24

24 x 2.5 = 60

60 x 3 = 180

Hence, the odd man in the given series is 12.

The given series is 1 6 27 124 650

1

1 + 2 x 2 = 6

6 + 3 x 3 = 27

27 + 4 x 4 = 124

124 + 5 x 5 = 645 (NOT 650)

Hence, the odd man in the given number series is 650.

The given series is 1000, 1012, 988, 1024, 978

1000

1000 + 12 = 1012

1012 - 24 = 988

988 + 36 = 1024

1024 - 48 = 976 (Not 978)

The given series is 15, 19, 27, 38, 55, 75

15

15 + 4 = 19

19 + 8 = 27

27 + 12 = 39

39 + 16 = 55

55 + 20 = 75

Hence, the odd number in the given series is 38.

The given number series is 5, 8, 40, 90, 664

5

5 - 1 x 2 = 8

8 - 3 x 4 = 20 (NOT 40)

20 - 5 x 6 = 90

90 - 7 x 8 = 664

The given number series is 152, 124, 96, 69, 40

152

152 - 28 = 124

124 - 28 = 96

96 - 28 = 68 (not 69)

68 - 28 = 40

Hence, the odd man in the given number series is 69.

The given number series is 3, 11, 80, 291, 803

$$\begin{gathered} 3 \\ 3 + 23 = 3 + 8 = 11 \\ 11 + 43 = 11 + 64 = 75 (not 80) \\ 75 + 63 = 75 + 216 = 291 \\ 291 + 83 = 291 + 512 = 803 \end{gathered}$$