Choose the option that shall come in place of the ? in the following series:
25WV52, 23TS32, 21QP12, ?, 17KJ71
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 19NM91
In a letter-number series, each part of the term follows its own rule, so the first number, the two letters and the last number are checked separately.
First numbers 25, 23, 21, ?, 17: each is 2 less, so 19
First letters W (23), T (20), Q (17), ?, K (11): each is 3 places back, so N (14)
Second letters V (22), S (19), P (16), ?, J (10): each is 3 places back, so M (13)
Last numbers 52, 32, 12, ?, 71: each is the first number with its digits reversed (25 → 52, 17 → 71), so 91
The missing term is 19 + N + M + 91 = 19NM91; Option (1), 19MN91, has the two letters the other way round.