Logical Reasoning · Micro-test

Alphabet and Letter Series

A letter series is a number series in disguise. Replace each letter with its position in the alphabet and the pattern nearly always shows itself.

10 questions · 5 minutes · instant scoring

What this topic actually tests

Write down the positions: A is 1, E is 5, J is 10, O is 15, T is 20, Y is 25, Z is 26. Remembering those five landmarks (E, J, O, T, Y) lets you place any letter in a second or two. Then look at the gaps between consecutive terms. A constant gap (A, C, E, G: plus two each time) is the simplest pattern. A gap that grows by one each time (A, B, D, G, K: plus 1, 2, 3, 4) is the next most common. A series running backwards has negative gaps (Z, X, V, T). When each term is a group of letters, treat each position within the group as its own series: in AZ, BY, CX the first letters run forward A, B, C and the second run backward Z, Y, X. Position questions ask for a letter a given number of places to the left or right of another, sometimes with the alphabet reversed. Do the arithmetic on positions and convert back at the end. For a letter midway between two others, average their positions: G is 7 and S is 19, so the letter midway is the 13th, M. With a reversed alphabet, draw the first few letters of the reversed line before counting, because 'left' and 'right' swap their usual meaning of earlier and later.

The common trap on this topic

The most common slip is an off-by-one count: 'the 7th letter to the right of J' is seven places after J, not seven places counting J itself. The second is assuming a constant gap after checking only the first two terms; always check at least three gaps before settling on the rule. The third is in reversed-alphabet questions, where moving left takes you towards Z, not towards A. Candidates who count in the usual direction land on the mirror-image wrong answer, which is nearly always among the options.

Alphabet and Letter Series: answers and explanations

What comes next in the series: A1, C3, E5, G7, ?
Answer: B. I9
The letters move forward two places at a time (A, C, E, G, I) and the numbers are the letters' positions in the alphabet, rising by two (1, 3, 5, 7, 9). The next term is I9.
What comes next in the series: Z, X, V, T, ?
Answer: B. R
The positions are 26, 24, 22, 20: each term moves two places back. The next is the 18th letter, R.
What comes next in the series: B, E, H, K, ?
Answer: D. N
The positions are 2, 5, 8, 11: a constant gap of three. The next is the 14th letter, N.
What comes next in the series: A, B, D, G, K, ?
Answer: A. P
The positions are 1, 2, 4, 7, 11, with gaps of 1, 2, 3 and 4. The next gap is 5, giving the 16th letter, P.
What comes next in the series: AZ, BY, CX, ?
Answer: D. DW
The first letters run forward (A, B, C, D) and the second letters run backward (Z, Y, X, W). The next term is DW.
Which letter is the 7th to the right of the 10th letter from the left in the English alphabet?
Answer: D. Q
The 10th letter from the left is J. Seven places to its right is the 17th letter, Q.
What comes next in the series: BDF, CEG, DFH, ?
Answer: B. EGI
Every letter in each group moves one place forward: B, C, D, E in the first position; D, E, F, G in the second; F, G, H, I in the third. The next group is EGI.
Which letter is exactly midway between G and S in the English alphabet?
Answer: B. M
G is the 7th letter and S is the 19th. The position midway is (7 + 19) ÷ 2 = 13, which is M. There are five letters on each side of M between G and S.
What comes next in the series: C, F, J, O, ?
Answer: D. U
The positions are 3, 6, 10, 15, with gaps of 3, 4 and 5. The next gap is 6, giving the 21st letter, U.
The English alphabet is written in reverse order, from Z on the left to A on the right. Which letter is the 5th to the left of the 12th letter from the right?
Answer: B. Q
With A at the right-hand end, the 12th letter from the right is L. In the reversed line, the letters to the left of L are M, N, O, P and Q in turn, so the fifth is Q. Counting in the usual direction gives G, the trap answer.

FAQ

What is the quickest way to find a letter's position in the alphabet?

Memorise the landmarks E = 5, J = 10, O = 15, T = 20, Y = 25 and count from the nearest one. M is 13, the last letter of the first half.

How do I solve a series made of groups of letters?

Split it. Read the first letter of every group as one series, the second letter as another, and so on. Each strand usually follows a simple rule of its own.

Are letter series asked in CLAT?

They are uncommon in recent CLAT papers, which are mostly passage-based, and take well under a minute each once practised. Entrance tests with an analytical reasoning section, such as MH-CET Law, ask them directly.

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