Aptitude - Odd Man Out and Series

Exercise :: Odd Man Out and Series - Missing No.

Insert the missing number.
1. 

16, 33, 65, 131, 261, (....)

A. 523
B. 521
C. 613
D. 721

Answer: Option A

Explanation:

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

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


2. 

10, 5, 13, 10, 16, 20, 19, (....)

A. 22
B. 40
C. 38
D. 23

Answer: Option B

Explanation:

There are two series (10, 13, 16, 19) and (5, 10, 20, 40), one increasing by 3 and the other multiplied by 2.

3. 

1, 4, 9, 16, 25, 36, 49, (....)

A. 54
B. 56
C. 64
D. 81

Answer: Option C

Explanation:

Numbers are 12, 22, 32, 42, 52, 62, 72.

So, the next number is 82 = 64.


4. 

2, 4, 12, 48, 240, (....)

A. 960
B. 1440
C. 1080
D. 1920

Answer: Option B

Explanation:

Go on multiplying the given numbers by 2, 3, 4, 5, 6.

So, the correct next number is 1440.


5. 

8, 7, 11, 12, 14, 17, 17, 22, (....)

A. 27
B. 20
C. 22
D. 24

Answer: Option B

Explanation:

There are two series (8, 11, 14, 17, 20) and (7, 12, 17, 22) increasing by 3 and 5 respectively.