Each number is twice the preceding one with 1 added or subtracted alternatively.

So, the next number is (2 x 261 + 1) = 523.

Except Granite all other options belong to the group of precious stones.

The given number series follows the pattern that,

24×0 + 4  = 4  

4×1  + 9   = 13

13×2 + 16 = 42

42×3 + 25  = 151

151×4 + 36 =  640

Therefore, the odd number in the given series is 41

In given Series, all the numbers except 54 are multiples of 5.

From the beginning, the next term comes by adding prime numbers in a sequence of 2, 3, 5, 7, 9, 11, 13... to its previous term. But 165 will not be in the series as it must be replaced by 166 since 153+13 = 166.

Terms at odd places are 5, 6, 7, 8 etc. and each term at even place is 16.

So, 9 is wrong.

In the given series numbers are arranged following the rule,

5 5 , 4 4 , 3 3 , 2 2 , 1 1

 Therefore, the missing number is 27.

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.

2.5 × 1 + 1 = 3.5

3.5 × 2 + 2 = 9

9 × 4 + 4 = 40

40 × 8 + 8 = 328

Here the series follows,

194

194 - (1x1 - 1) = 194

194 - (2x2 - 1) = 191

191 - (3x3 - 1) = 183

183 - (4x4 - 1) = 168

168 - (5x5 - 1) = 144