# Aptitude - Odd Man Out and Series

Exercise : Odd Man Out and Series - Find Wrong No.
Directions to Solve
Find out the wrong number in the series.

11.
64, 71, 80, 91, 104, 119, 135, 155
71
80
104
119
135
Explanation:

Go on adding 7, 9, 11, 13, 15, 17, 19 respectively to obtain the next number.

So, 135 is wrong.

12.
15, 16, 34, 105, 424, 2124, 12756
16
34
105
424
2124
Explanation:

2nd term = (1st term) x 1 + 1 = 15 x 1 + 1 = 16.

3rd term = (2nd term) x 2 + 2 = 16 x 2 + 2 = 34.

4th term = (3th term) x 3 + 3 = 34 x 3 + 3 = 105.

5th term = (4th term) x 4 + 4 = 105 x 4 + 4 = 424

6th term = (5th term) x 5 + 5 = 424 x 5 + 5 = 2125

6th term should 2125 instead of 2124.

13.
10, 26, 74, 218, 654, 1946, 5834
26
74
218
654
1946
Explanation:

2nd term = (1st term) x 3 - 4 = 10 x 3 - 4 = 26.

3rd term = (2nd term) x 3 - 4 = 26 x 3 - 4 = 74.

4th term = (3th term) x 3 - 4 = 74 x 3 - 4 = 218.

5th term = (4th term) x 3 - 4 = 218 x 3 - 4 = 650.

5th term must be 650 instead of 654.

14.
2880, 480, 92, 24, 8, 4, 4
480
92
24
8
4
Explanation:

Go on dividing by 6, 5, 4, 3, 2, 1 respectively to obtain the next number.

Clearly, 92 is wrong.

15.
3, 7, 15, 27, 63, 127, 255
7
15
27
63
127