Odd Man Out Questions

With close observation, you will note that each number in the list is in the middle of two prime numbers. Thus:

4 is in the middle of 3 and 5, 6 is in the middle of 5 and 7, 12 is in the middle of 11 and 13, 18 is in the middle of 17 and 19, 30 is in the middle of 29 and 31. 42 is in the middle of 41 and 43, 60 is in the middle of 59 and 61.

Therefore, the next number would be the one that is in the middle of the next two prime numbers, which is 72 (which is in the middle of 71 and 73).

The given number series is 10, 21, 54, 109, 189

The series follows a pattern that

10 + 11 = 21

21 + 33 = 54

54 + 55 = 109

109 + 77 = 186

Hence the wrong number in the given number series is 189.

Here the series follow the rule that

12+22 = 5

32+42 = 25

52+62 = 61

72+82 = 113

SO NEXT IS, 92+102 = 181

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 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.

Here the given number series is 6, 3, 3, 4.5, 10

The odd one in the given series is 10

The pattern it follows is

6

6 x 0.5 = 3

3 x  1  = 3

3 x 1.5 = 4.5

4.5 x 2 = 9

Hence, the odd number is 10.