Letter and Symbol Series Questions and Answers

Answer: C

Correct answer: NML

Each group holds three consecutive letters in descending order, and successive groups begin three places further on: E, H, K. The next begins at N and reads NML. The two rules - the internal reversal and the three-step between groups - are independent, and the answer has to honour both. MLK starts one place too early. The internal reversal and the three-step between groups are independent rules, and an answer must satisfy both to be correct.

Answer: D

Correct answer: IHG

Each group is three consecutive letters in descending order, and the groups themselves move backwards three places at a time: they begin at R, O, L. The next begins at I and reads IHG. Everything in this series descends, both within the groups and between them, which makes it easy to lose a step; listing the leading letters R, O, L, I first is the safest route. Listing the leading letters R, O, L and I first separates the two descending motions and makes the answer straightforward.

Answer: A

Correct answer: 10J

Each term pairs an even number with the letter at that position in the alphabet: 2 with B, 4 with D, 6 with F, 8 with H. The next even number is 10 and the tenth letter is J, so the term is 10J. Because the letter is fixed by the number, the two halves cannot be counted independently - which is exactly what 10I gets wrong. Because the letter is fixed by the number, the two halves cannot be counted independently, and an inconsistent pairing can be rejected on sight.

Answer: B

Correct answer: 15O

The numbers are the multiples of three - 3, 6, 9, 12 - and each letter sits at that position in the alphabet: C is 3rd, F is 6th, I is 9th, L is 12th. The next multiple is 15 and the 15th letter is O, giving 15O. The pairing makes the answer self-checking: count fifteen letters and confirm it is O before writing it down. The pairing is self-checking: counting fifteen letters into the alphabet confirms O before the answer is committed to.

Answer: C

Correct answer: 25Y

The numbers climb in fives and each letter stands at the matching alphabet position: 5 is E, 10 is J, 15 is O, 20 is T. The next number is 25 and the 25th letter is Y, giving 25Y. The series stops naturally here, since a further five would pass the end of the alphabet. 25X pairs the right number with the letter one place short. The series stops naturally at 25, since a further five would carry it past the end of the alphabet with no letter to pair.

Answer: D

Correct answer: 20T

The numbers are the multiples of four and each letter occupies that position in the alphabet: 4 is D, 8 is H, 12 is L, 16 is P. The next multiple is 20 and the 20th letter is T, so the term is 20T. Because each half determines the other, an answer can be checked without reference to the earlier terms at all. Each half of the term determines the other, so an answer can be verified without reference to any of the earlier terms.