Letter and Symbol Series Questions and Answers

Answer: D

The series is ABC, GFE, MJG, SNI, ?. Each letter in the cluster follows its own rule. The first letters are A, G, M, S, so each is 6 places after the one before, and the next is Y. The second letters are B, F, J, N, each 4 places on, so the next is R. The third letters are C, E, G, I, each 2 places on, so the next is K.

The cluster that replaces the question mark is therefore YRK. The options ZRK and SRK break the rule for the first letter (it must be Y), and YRL breaks the rule for the third (it must be K). Only YRK follows all three rules.

Answer: B

The blanks are filled by G and P, so the answer is GP.

Take the first letters: A, B, D, _, K, P. They move forward by 1, 2, 3, 4 and 5 places (A to B is +1, B to D is +2, D to G is +3, G to K is +4, K to P is +5), so the first blank is G. Take the second letters: Z, Y, W, T, _, K. They move back by 1, 2, 3, 4 and 5 places (Z to Y, Y to W, W to T, T to P, P to K), so the second blank is P.

The other options, HP, GO and HQ, each fail at least one of the two letter patterns.

Answer: B

The next term is HA.

The first letters of the terms after the first form the Fibonacci numbers 1, 2, 3, 5 and 8, which are the letters A, B, C, E and H. The second letters follow a pair-wise pattern: A, A, then F, F, then A, A. So the sixth term has first letter H and second letter A.

IA, EB and DB break either the Fibonacci pattern of the first letters or the pairing of the second letters.

Another way to see it is to look at the pairs of letters one by one: AA, BA, CF, EF, then HA. The first letters A, B, C, E, H are the 1st, 2nd, 3rd, 5th and 8th letters, the Fibonacci numbers, so the next is H. The second letters repeat in pairs, so after two Fs come two As, and the next second letter is A.

Answer: B

The missing cluster is RRV. Write each letter as its place in the alphabet and look at each position of the clusters separately. First letters: H(8), M(13), ?, W(23), B(2, that is 28 after wrapping): each step adds 5, so the third is R(18). Second letters: X(24), U(21), ?, O(15), L(12): each step subtracts 3, so the third is R(18). Third letters: K(11), C(3), ?, P(16), K(11): the steps are −8, −7, −6, −5, so the third is 3 − 7 = −4, which is 22 after wrapping, V. The cluster is RRV. RRU, RSV and SRV each break at least one of these three patterns.

Answer: B

The missing group is TUVWX.

Two patterns run together. Each group is one letter longer than the last: BC has 2 letters, FGH 3, LMNO 4, so the next has 5. And the gap between groups grows by one each time: after C, the letters D and E are skipped (2); after H, I, J and K are skipped (3); so after O, four letters, P, Q, R and S, are skipped, and the next group starts at T.

That gives T, U, V, W, X. RSTUV and STUVW start too early (skipping two or three letters after O), and UVWXY starts too late (skipping five).

Answer: D

The missing term is VH15. Take the three parts of each term separately. First letters: P, Q, S, ?, Z move by +1, +2, +3, +4, so the missing first letter is V. Second letters: Q, M, J, ?, G move by -4, -3, -2, -1, giving H. Numbers: 1, 3, 7, ?, 31 follow the rule double and add 1: 1, 3, 7, 15, 31, so the number is 15. The term is VH15. UI17, UG28 and VH25 fail at least one of the three rules: the number 25 is not 15, and 17 and 28 do not fit the doubling pattern.

Answer: A

The next cluster is AN.

In the first letters G, I, M, S the jumps are +2, +4 and +6, so the next jump is +8: S is the 19th letter and 19 + 8 = 27, which wraps round to A. In the second letters T, V, Z, F the jumps are again +2, +4 and +6, so the next jump is +8: F is the 6th letter and 6 + 8 = 14, which is N.

YL, AL and YN each get one of the two letters wrong, so only AN follows both patterns.

A quick check is to write the letters of the two series side by side: G-T, I-V, M-Z, S-F. Each pair moves by the same amount in both letters at every step, so the same +8 jump applies to both letters of the answer. Wrapping past Z to A is needed in both positions, which is why the answer starts with A.

Answer: D

The pair that follows the same logic is BUYER-UBYER-BUYRE.

In AVOID-VAOID-AVODI, the first step swaps the first two letters (AVOID to VAOID), and the second step swaps the first two letters again and also the last two letters (VAOID to AVODI). BUYER to UBYER swaps the first two letters, and UBYER to BUYRE swaps the first two again and the last two (E and R), which is the same logic.

The other options reverse or scramble whole words rather than swapping those pairs of letters.

Check the rule on the remaining options to see why they fail. In CALIF-LIFAC the letters are moved in blocks, and in DREAM-MAERD the whole word is reversed. EXIST-IXSTE shifts letters round in a cycle. None of them swaps only the first two and then the first two together with the last two letters, as the given triad does.

Answer: A

The next term is OV.

Write the letters as their positions in the alphabet:

The first letters rise by 2, 3, 4, so the next rise is 5: 10 + 5 = 15, O. The second letters rise by 3, 4, 5, so the next rise is 6: 16 + 6 = 22, V.

OW and PW put the second letter at 23, and PV and PW put the first at 16, each breaking one of the two growing gaps.

Answer: A

The missing letters are abba.

Filling the blanks in order with a, b, b, a gives

abba baab ab baba aba = abba baab abba baab a

The series is the block 'abba' followed by its mirror 'baab', repeated. Trying abab or aabb breaks the abba/baab alternation (aabb, for instance, makes the second block baaa), and ccac brings in a letter that does not occur in the series at all.