In the following series find one number that is wrong:
(A) 3 (B) 13 (C) 37 (D) 86
Generally in the series problems, if we do not find any immediate logic, try out finding the differences of consecutive numbers:
Except 10 and 24, all others are squares of odd numbers.
10 and 24 are resulted from the differences of 3,13 and 13,37 respectively. Here if ‘13’ is replaced with ‘12’, we get the series of differences of consecutive numbers: 1,9,25,49,81,121, which is perfect one. This is a series of squares of consecutive odd numbers.
Hence the odd one out of the given set of numbers is ‘13’Answer (B)