# number series logical reasoning questions

6.

2 3 4 5 6 4 8
A.     9 10    B.     4 8
C.     10 4    D.     9 4
E.     8 9

Explanation:

This is an alternating addition series with a random number, 4, interpolated as every third number. In the main series, 1 is added, then 2 is added, then 1, then 2, and so on.
7.

17 17 34 20 20 31 23
A.     26 23    B.     34 20
C.     23 33    D.     27 28
E.     23 28

Explanation:

This is an alternating subtraction series with repetition. There are two different patterns here. In the first, a number repeats itself; then 3 is added to that number to arrive at the next number, which also repeats. This gives the series 17, 17, 20, 20, 23, and so on. Every third number follows a second pattern, in which 3 is subtracted from each number to arrive at the next: 34, 31, 28.
8.

6 20 8 14 10 8 12
A.     14 10    B.     2 18
C.     4 12    D.     2 14
E.     14 14

Explanation:

This is an alternating addition and subtraction series. In the first pattern, 2 is added to each number to arrive at the next; in the alternate pattern, 6 is subtracted from each number to arrive at the next.
9.

21 25 18 29 33 18
A.     43 18    B.     41 44
C.     37 18    D.     37 41
E.     38 41

Explanation:

This is a simple addition series with a random number, 18, interpolated as every third number. In the series, 4 is added to each number except 18, to arrive at the next number.