Logical Reasoning - Number Series

Exercise :: Number Series - Type 4

Find the number that fits somewhere into the middle of the series. Some of the items involve both numbers and letters
1. 

Look at this series: F2, __, D8, C16, B32, ... What number should fill the blank?

A. A16
B. G4
C. E4
D. E3

Answer: Option C

Explanation:

The letters decrease by 1; the numbers are multiplied by 2.

2. 

Look at this series: 664, 332, 340, 170, ____, 89, ... What number should fill the blank?

A. 85
B. 97
C. 109
D. 178

Answer: Option D

Explanation:

This is an alternating division and addition series: First, divide by 2, and then add 8.

3. 

Look at this series: V, VIII, XI, XIV, __, XX, ... What number should fill the blank?

A. IX
B. XXIII
C. XV
D. XVII

Answer: Option D

Explanation:

This is a simple addition series; each number is 3 more than the previous number.

4. 

Look at this series: 70, 71, 76, __, 81, 86, 70, 91, ... What number should fill the blank?

A. 70
B. 71
C. 80
D. 96

Answer: Option A

Explanation:

In this series, 5 is added to the previous number; the number 70 is inserted as every third number.

5. 

Look at this series: 8, 43, 11, 41, __, 39, 17, ... What number should fill in the blank?

A. 8
B. 14
C. 43
D. 44

Answer: Option B

Explanation:

This is a simple alternating addition and subtraction series. The first series begins with 8 and adds 3; the second begins with 43 and subtracts 2.