Letter Series Reasoning Tricks: Missing Letter and Alphabet Pattern Questions for SSC CGL, CHSL

A letter series is a row of letters that follow a rule, and you find the next or the missing letter. The trick is to change the letters into numbers and look for a number pattern, just like a number series. These letter series tricks for SSC explain the common patterns, the wrap-around rule after Z and the solved questions.

Letter Positions

The letters E, J, O, T and Y are at the positions 5, 10, 15, 20 and 25. The letter after Z is A (position 27 is 1).

Common Patterns

Method

1. Write the position number under each letter.
2. Find the difference between the neighbouring numbers.
3. If the differences are the same, it is a constant step. If they grow, it is a growing step.
4. If the series goes up and down, check the odd and the even places separately.
5. After Z, count again from A (add 26 if needed).

Solved Examples

Example 1. B, E, H, K, ?
The positions are 2, 5, 8, 11. The step is +3. The next is 14, which is N.

Example 2. A, D, I, P, ?
The positions are 1, 4, 9, 16 (the squares). The next is 25, which is Y.

Example 3. C, F, I, L, ?
The step is +3. The next is O.

Example 4. J, K, M, P, T, ?
The steps are +1, +2, +3, +4. The next step is +5, so 20 + 5 = 25, which is Y.

Example 5. A, Z, B, Y, C, ?
The odd places have A, B, C and the even places have Z, Y, X. The next is X.

Tips

• Squares (1, 4, 9, 16, 25) often make letter series: A, D, I, P, Y.
• If the numbers go above 26, subtract 26.
• Check the two-letter pairs by treating the first and the second letters as two separate series.

Quick Tips

• Change the letters into numbers.
• Check the differences and then the growing steps.
• Use two series for alternate patterns.
• Subtract 26 when you cross Z.

Quick Revision Points

• The letter after Z is A.
• E J O T Y are 5, 10, 15, 20, 25.
• The squares 1, 4, 9, 16, 25 give A, D, I, P, Y.
• Alternate series have two separate patterns.
• Check the differences first.

Practice Questions With Answers

1. B, D, F, H, ?
   Answer: J
2. Z, Y, X, W, ?
   Answer: V
3. A, C, F, J, ?
   Answer: O
4. AB, CD, EF, ?
   Answer: GH
5. M, N, P, S, ?
   Answer: W
6. B, D, G, K, ?
   Answer: P
7. Z, W, T, Q, ?
   Answer: N
8. AZ, BY, CX, ?
   Answer: DW
9. E, G, J, N, ?
   Answer: S
10. A, E, I, M, ?
    Answer: Q

How to Practise This Chapter

Practise 10 questions every day and write the steps on paper. Then attempt timed sets from our practice papers and the previous year papers page. See all topics on the Verbal Reasoning notes page and the next topic Letter Cluster Series. Learn the letter positions from the Alphabet Test note first.

Frequently Asked Questions

What is a letter series?

It is a row of letters that follow a rule, and you find the next or the missing letter.

How do I solve a letter series?

Change the letters into numbers and find the pattern of the differences.

What comes after Z in a series?

The series starts again from A.

What is a growing step series?

A series in which the step increases, such as +1, +2, +3 and +4.

How do I solve an alternate series?

Check the odd and even places separately.

Which letters are at the positions 5, 10, 15, 20 and 25?

E, J, O, T and Y.

What is the next letter in A, D, I, P?

Y.

Is letter series asked in SSC exams?

Yes. Letter series is asked in SSC CGL, CHSL and MTS reasoning papers.

How much time should I take?

About 30 seconds.

What are the common mistakes?

Not counting after Z and checking only the first difference.

How can I improve my speed?

Learn the positions table and practise 10 series daily.

How is it different from number series?

It uses letter positions, so you must convert the letters first.