# 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

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

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

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

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