$$\begin{gathered} 3 \\ 3 2 + 3 = 12 \\ 5 \\ 5 2 + 5 = 30 \end{gathered}$$

The given series follows the pattern that,

18, 97, 26, 91, ?, 83

=> 18 + 8 = 26

=> 97 - 8 = 91

=> 26 + 8 = 34

=> 91 - 8 = 83

Hence, the missing number is 34.

48, 54, 63, 81 and 105 are divisible by 3 but not 35.

Except 437 all others are prime numbers.

The series given follow the pattern

+2, +2+4, +2+4+6, +2+4+6+8, +2+4+6+8+10,...

Here ? = 7 + 2 + 4 = 13.

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.

4       30       ?     1440       7195      71940

Here the given series follows a pattern of

4

4 x 10 - 10 = 30

30 x 5 - 5  = 145

145 x 10 - 10 = 1440

1440 x 5 - 5 = 7195

7195 x 10 - 10 = 71940

Hence, the missing number is 145

Given nuber series is 15, 30, ? , 40, 8, 48 

Here the number series follows a pattern that

15

15 x 2 = 30

30  ÷ 3 = 10

10 x 4 = 40

40  ÷ 5 = 8

8 x 6 = 48

Hence, the missing number in the series is 10.

Here the given number series follows a pattern of two alternate series.

1. 7 19 31 ...(Difference of 12)

2. 9 18 27 ...(Difference of 9)

Here the odd number is 29 instead of 27

And the next number is 31 + 12 = 43 & 27 + 9 = 36

The given series 

12   24   26.5   79.5   ?   330 follows a pattern that,

12 x 2 = 24

24 + 2.5 = 26.5

26.5 x 3 = 79.5

79.5 + 3 = 82.5

82.5 x 4 = 330

Hence, the missing number is 82.5