Letter Series

Letter series is a logical arrangement of letters of English alphabet arranged in a specified pattern. Letter Series are a sequential order of letters, numbers or both arranged such a way that each term in the series is obtained according to some specific rules. These rules can be based on mathematical operations, place of letters in alphabetical order etc. In this, a series of letters, groups of letters or combination of letters and numbers is given. 

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

Types of Letter series:

Type-1: Alphabet series

In this type, letters of English alphabet are arranged in a particular pattern like reverse order of letters, skipping of letters, position of letters in alphabetical order etc.

One lettered series 

In One lettered series each term contains one letter and follows a certain pattern.

Example : 

Find the next term in the series.

A, D, G, J, ?

Solution : M

letter-and-symbol-series-logical-reasoning-introduction---letter-and symbol-series-problems

Two lettered series

In Two lettered series each term contains two letter and follows a certain pattern.We have to find out the next term according to that pattern.

Example : Find the next two terms of the given series.

Z, S, W, O, T, K, Q, G, ?, ?

Solution : N, C

The given series is a combination of two series.

I. Z, W, T, Q, ?   and   II. S, O, K, G, ?

letter-and-symbol-series-logical-reasoning-introduction---letter-and symbol-series-problems

Three lettered series:

In Three lettered series each term contains three letter and follows a certain pattern.We have to find out the next term according to that pattern.

Example: Find the missing term in the given series.

ABP, CDQ, EFR, ?

Solution : GHS 

The given series is a combination of three series.

I.   A, C, E, ?   and   II. B, D, F, ?
III. P, Q, R, ?

Now,

letter-and-symbol-series-logical-reasoning-introduction---letter-and symbol-series-problems

Type-2: Continuous pattern series

In this type, a series of small/capital letters are given which follow a particular pattern. However, some letters are missing from the series. The series follow a specific pattern and candidates are required to find the letters which should come in place of the blank spaces or question marks.

Example : These questions are based on the letter series. In each of these series, some of the letters are missing. Select the correct alternatives.

1. abca_bcaab_ca_bbc_a

(a) ccaa        (b) bbaa   
(c) abac        (d) abba

Solution:  abac

Pattern of the series is as shown below

abc / aabc / aabbc / aabbcc / a => abac

2. _cb_ca_bacb_ca_bac_d

(a) badddb        (b) bbbddd   
(c) addddb        (d) addbbb

Solution:  addddb

Pattern of the series is as shown below

acbd / cadb / acbd / cadb / acbd  =>  addddb

The sequence is made of repetition of two blocks 'acbd' and 'cadb' alternatively.

Type-3: Mixed series (Alpha-numeric series)

In this type, the series is based on the combination of both the letters and numbers. Each term in the series follows a certain pattern based on either the alphabetical position of the letters or the numbers in different correlation.

Example : Replace the question mark (?) in the following series with suitable option.

C-3, E-5, G-7, I-9, ?, ?

Solution : K-11, M-13

Pattern of the series is as shown below

 

letter-and-symbol-series-logical-reasoning-introduction---letter-and symbol-series-problems

 

In this series, every letter is given its alphabetical position and one letter is skipped in between each term.