Letter and Symbol Series Questions and Answers

Answer: C

Correct answer: U&

The symbol never changes, so the whole of the pattern is in the letters, which advance two places at a time: M, O, Q, S. The next is U, giving U&. A constant element in a compound series is there to distract; identifying it as constant early removes half the problem. T is the immediately following letter and would fit a single step. A constant element in a compound term carries no information and is placed there to distract, so identifying it as constant is the first move.

Answer: D

Correct answer: F

The alphabet positions double each time: B is 2, D is 4, H is 8, P is 16. Doubling again gives 32, which is beyond the alphabet, so the count wraps round: 32 minus 26 is 6, which is F. The wrap is what makes this hard, because the series suddenly returns to the beginning of the alphabet after climbing steadily. Anyone who stops at 32 without wrapping finds no letter at all and guesses.

Answer: A

Correct answer: E

Each position is double the last plus one: A is 1, C is 3, G is 7, O is 15. Next is 31, which exceeds 26, so it wraps to 31 minus 26, that is 5, which is E. The doubling is easier to see if the positions are written as one less than a power of two: 1, 3, 7, 15, 31. Without the wrap the series has no next term. Writing the positions as 1, 3, 7, 15, 31 shows them to be one less than the powers of two, which makes the next term immediate.

Answer: B

Correct answer: V

The positions double at every step: C is 3, F is 6, L is 12, X is 24. Twice 24 is 48, which wraps round to 48 minus 26, that is 22, giving V. Doubling series reach the end of the alphabet quickly, so a wrap is almost always involved by the fourth or fifth term; expecting one is half the battle. Doubling series pass the end of the alphabet within four or five terms, so a wrap should be expected rather than treated as an irregularity.

Answer: C

Correct answer: L

The positions double each time, wrapping when they pass 26. D is 4, H is 8, P is 16, then 32 wraps to 6, which is F. Doubling 32 gives 64, and subtracting 26 twice leaves 12, which is L. The series has already wrapped once before the question mark, which is the clue that the rule involves wrapping at all - without it the fourth term could not be F. The wrap before the question mark is the clue that the alphabet is being treated as a loop; without it the fourth term could not be F.

Answer: D

Correct answer: JI

Each pair is two consecutive letters written in reverse, and the pairs advance two places at a time: BA, DC, FE, HG. The next pair takes J and I, giving JI. The reversal is easy to lose when writing the answer, which is why IJ - the right letters in the wrong order - is the most attractive distractor. The reversal is easy to lose when writing the answer down, which is why the same two letters in the wrong order are always among the options.

Answer: A

Correct answer: RQ

The pairs run backwards through the alphabet, two letters at a time, with each pair written in descending order: Z and Y, then X and W, then V and U, then T and S. The next pair is R and Q, giving RQ. Both the direction of the series and the order within each pair are descending, and keeping the two consistent is where the errors arise. Everything descends here, both within each pair and between pairs, so listing the leading letters Z, X, V, T and R first is the safest route.

Answer: B

Correct answer: LKJ

Each group is three consecutive letters written in reverse, and the groups step forward three places at a time: the highest letters are C, F, I. The next group is built on L, so it reads LKJ. Reading the groups by their first letter - C, F, I, L - reduces the problem to a simple three-step series. JKL has the right letters but restores them to ascending order. Reading the groups by their highest letter reduces the problem to the three-step series C, F, I, L, after which the reversal is mechanical.

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.