1,2,3,6,9,18, x ,54 - Number Series - Series Completion - Verbal Reasoning question

A. 18

B. 36

C. 81

D. 27

E. None of the above

Answer: D. 27

The numbers are alternatively multiplied by 2 and 3/2.
So, 1 X 2 = 2,
2 X 3/2 = 3,
3 X 2 = 6,
6 X 3/2 = 9,
so missing number = 18 X 3/2 = 27

Posted in: Number Series - Series Completion - Verbal Reasoning