Series Completion - Verbal and Reasoning

Directions to SolveIn this type of questions, one term in the number series is wrong. Find out the wrong term.
Q1:

89, 78, 86, 80, 85, 82, 83

A 83

B 82

C 86

D 78

ANS:C - 86

Explanation: The correct pattern is - 11, + 9, - 7, + 5, - 3, + 1. So, 86 is wrong and must be replaced by (78 + 9) i.e. 87.