# Logical Reasoning - Number Series

### Exercise :: Number Series - Type 1

In each series, look for the degree and direction of change between the numbers. In other words, do the numbers increase or decrease, and by how much
16.

Look at this series: 80, 10, 70, 15, 60, ... What number should come next?

 A. 20 B. 25 C. 30 D. 50

Explanation:

This is an alternating addition and subtraction series. In the first pattern, 10 is subtracted from each number to arrive at the next. In the second, 5 is added to each number to arrive at the next.

17.

Look at this series: 2, 6, 18, 54, ... What number should come next?

 A. 108 B. 148 C. 162 D. 216

Explanation:

This is a simple multiplication series. Each number is 3 times more than the previous number.

18.

Look at this series: 5.2, 4.8, 4.4, 4, ... What number should come next?

 A. 3 B. 3.3 C. 3.5 D. 3.6

Explanation:

In this simple subtraction series, each number decreases by 0.4.

19.

Look at this series: 8, 6, 9, 23, 87 , ... What number should come next?

 A. 128 B. 226 C. 324 D. 429

Explanation:

8 x 1 - 2 = 6
6 x 2 - 3 = 9
9 x 3 - 4 = 23
23 x 4 - 5 = 87
87 x 5 - 6 = 429 ...