Letter and Symbol Series Questions and Answers

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.

Answer: D

The missing cluster is T G 40.

First letters: E (5), H (8), M (13), ?, C. The gaps are +3, +5, +7, +9, so the missing letter is \(13 + 7 = 20\), T, and then \(20 + 9 = 29\), which wraps round to 3, C, as given.

Second letters are the opposites of the first (letters whose positions add to 27): E-V, H-S, M-N, so T pairs with G. Numbers are twice the first letter's position: 10, 16, 26, so T gives 40, and C (29 on the wrap) gives 58, as given.

T H and S G break the letter rule, and 36 breaks the number rule.

Answer: C

The missing letters are z y z x y.

Filling them in gives: yyzzx xxyyz zzxxy yyzzx. The series is made of blocks of five letters; each block has two of one letter, two of the next and one of the third, and each block starts with the letter its predecessor ended on: yyzzx, then xxyyz, then zzxxy, then yyzzx again.

Each of the other options breaks this pattern in at least one block; for instance x y z y x leaves the first block as yyzxx.

Answer: A

The series adds the next letter of the alphabet at each step: a, then ab, then abc, then abcd, then abcde. So the next term adds f to give abcdef. The option abcdfe has the last two letters in the wrong order, and Abcfed and Abcdef start with a capital letter while every term of the series is in small letters, so they do not continue the pattern. The answer is abcdef, option A.

Answer: D

The missing term is UQ120. Take the three parts of each term separately. The first letters A, C, G, M move by 2, 4 and 6 places, so the next move is 8 places, giving U. The second letters G, H, J, M move by 1, 2 and 3 places, so the next move is 4 places, giving Q. The numbers 48, 63, 80, 99 differ by 15, 17 and 19, so the next difference is 21 and the number is 99 + 21 = 120. The options VR122, VS124 and UQ112 each fail on at least one of the three parts, and only UQ120 satisfies all of them.

Answer: B

In each term the first letter moves three places forward, the second moves three places back and the number is the next prime: F P 11, I M 13, L J 17, then O G 19, and R D 23 follows.

\[ L+3=O,\ J-3=G,\ \text{next prime after } 17 = 19 \]

The missing term is O G 19. The options with 21 break the prime sequence, and P H or P G shift the first letter by four places.

Answer: D

The blanks are filled with a, a, b, c, a, c, b, d, c, d (option D). The series is the seven-letter block abbcade repeated. Writing the given series with the blanks filled in this way gives abbcade abbcade abbcade abbcade abbcade, and every printed letter agrees with it: the first blank takes a to start the block, the second takes a, and so on through the string.

Option A starts with c, which would make the first block cbbc..., not matching the b b c after it, and options B and C fail at the first or second blank in the same way, because the letters after each blank (b b c, d e a) fix the block abbcade. Only the sequence a, a, b, c, a, c, b, d, c, d completes all five repeats.