# number series logical reasoning questions

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.