Logical Reasoning - Number Series

Exercise : Number Series - Type 1
Directions to Solve
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?
20
25
30
50
Answer: Option
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?
108
148
162
216
Answer: Option
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?
3
3.3
3.5
3.6
Answer: Option
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?
128
226
324
429
Answer: Option
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 ...