Series Completion - Verbal and Reasoning

Directions to SolveChoose the correct alternative that will continue the same pattern and replace the question mark in the given series.
Q1:

6, 18, 3, 21, 7, 56, ?

A 8

B 9

C 63

D 64

ANS:A - 8

Explanation: Each term at an even place in the series is the product of its two adjacent terms. Thus, if the missing term be x, then we have : 7 x x = 56 or x = 56 ÷ 7 = 8.