Hard
Find the wrong term in the series: 89, 78, 86, 80, 85, 82, 83
Explanation
Explanation
This is two interleaved series. The terms at odd positions (1st, 3rd, 5th, 7th) should decrease by 2 each time: 89, 87, 85, 83 - but the 3rd term is given as 86 instead of 87. The terms at even positions (2nd, 4th, 6th) correctly increase by 2: 78, 80, 82. So the wrong term is 86.
PRO TIP
Re-check your working by substituting the answer back into the original question.