Letter series is a logical arrangement of letters of English alphabet arranged in a specified pattern.
In this, a series of letters, groups of letters or combination of letters and numbers is given. Each group or single element is called term. The terms of the series form a certain pattern. So first required to identify this pattern and find the missing term in the given series which will satisfy the pattern.

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.

We have to find out the next term according to that pattern.

Example: What is the next letter in the series B, F, J, N, _______ ?

1) R

2) T

3) Q

4) S

Answer:1) R

Explanation:

B = 2, F = 6, J = 10, N = 14 .
Here the difference between the letter is 4. So the answer is 14 + 4 = 18 which is R.

Example: What is the next letter in the series B, C, E, G, ______ ?

1) J

2) I

3) K

4) M

Explanation:

B = 2, C = 3, E = 5, G = 7 .
Here the letters are consecutive primes. So the next prime number is 11 which is K.

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.

1) GR

2) GQ

3) HQ

4) HR

Answer:2) GQ

Explanation:

C = 3, D = 4, E = 5, F = 6 .
M = 13, N = 14, O = 15, P = 16 .
So next term is G = 7 and Q = 17 .

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: What is the next letter in the series CNL, BLI, AJF, ZHC, _______ ?

1) XDY

2) YFZ

3) YFA

4) XFY

Answer: 2) YFZ

Explanation:

C = 3, B = 2, A = 1, Z = 26 . ( Decreasing by 1 ) So next letter is 25, which is Y.
N = 14, L = 12, J = 10, H = 8 . ( Decreasing by 2 ) So next letter is 6, which is F.
L = 12, I = 9, F = 6, C = 3 . ( Decreasing by 3 ) So next letter is 26, which is Z.

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.

In each of the following letter series, some of the letters are missing which are given in that order as one of the alternatives below it. Choose the correct alternative.

1._ stt _ tt _ tts _

A)tsts

B)ttst

C)sstt

D)tsst

Answer:D

Explanation:

The series is tst/tst/tst/tst. Thus, the pattern 'tst' is repeated.

2. gfe _ ig _ eii _ fei _ gf_ ii

A)eifgi

B)figie

C)ifgie

D)ifige

Answer:Option C

Explanation:

The series is gfeii/gfeii/gfeii/gfeii. Thus, the pattern 'gfeii' is repeated.

3. _ a _ b _ abaa _ bab _ abb

A)aaabb

B)ababb

C)babab

D)babba

Answer:Option D

Explanation:

4.How many person (s) sit (s) between V and the Doctor?

A)None

B)Three

C)Two

D)One

Answer:B

Explanation:

The series is baa/bba/baa/bba/baa/bb. Thus, the pattern baa/bba is repeated.

4. abca _ bcaab _ ca _ bbc _ a

A)ccaa

B)bbaa

C)abac

D)abba

Answer:C

Explanation:

The series is abc/aabc/aabbc/aabbcc/a.

5. _ tu _ rt _ s _ _ usrtu _

A)rtusru

B)rsutrr

C)rsurtr

D)rsurts

Answer:D

Explanation:

The series rtus/rtus/rtus/rtus. Thus, the pattern 'rtus' is repeated.

6. _ _aba _ _ ba _ ab

A)abbba

B)abbab

C)baabb

D)bbaba

Answer:B

Explanation:

The series is ab/ab/ab/ab/ab/ab. Thus, the pattern 'ab' is repeated.

7. c _ bbb _ _ abbbb _ abbb _

A)aabcb

B)abccb

C)abacb

D)baebb

Answer:B

Explanation:

The series is cabbbb/cabbbb/cabbbb. Thus, the pattern 'cabbbb' is repeated.

8. _ bbca _ bcca _ ac _ a _ cb

A)abeba

B)acbab

C)bacab

D)bcaajb

Answer:B

Explanation:

The series is abbc/ac/bcca/ba/caab/cb

9. a _ bbc _ aab _ cca _ bbcc

A)bacb

B)acba

C)abba

D)caba

Answer:B

Explanation:

The series is aabbcc/aabbcc/aabbcc. Thus, the pattern 'aabbcc' is repeated.

10. ac _ cab _ baca _ aba _ acac

A)aacb

B)aebe

C)babb

D)bcbb

Answer:A

Explanation:

The series is acac/abab/acac/abab/acac. Thus, the pattern acac/abab is repeated.

11. _ aa _ ba _ bb _ ab _ aab

A)aaabb

B)babab

C)bbaab

D)bbbaa

Answer:C

Explanation:

The series is baab/baab/baab/baab. Thus, the pattern 'baab' is repeated.

12. c _ bba _ cab _ ac _ ab _ ac

A)abebe

B)acbcb

C)babec

D)bcacb

Answer:B

Explanation:

The series is cabbac/cabbac/cabbac. Thus, the pattern 'cabbac' is repeated.

13. ba _ cb _ b _ bab _

A)acbb

B)bacc

C)bcaa

D)cabb

Answer:B

Explanation:The series is babc/babc/babc. Thus, the pattern 'babc' is repeated.

14. _ bc _ ca _ aba _ c _ ca

A)abcbb

B)bbbec

C)bacba

D)abbec

Answer:A

Explanation:

The series is abc/bca/cab/abc/bca, Thus, the letters change places in a cyclic order.

15. ab _ _ baa _ _ ab _

A)aaaaa

B)aabaa

C)aabab

D)baabb

Answer:B

Explanation:

The series is aba/aba/aba/aba. Thus, the pattern 'aba' is repeated.

16. ab _ aa _ bbb _ aaa _ bbba

A)abba

B)baab

C)aaab

D)abab

Answer:B

Explanation:

The series is abb/aaabbb/aaaabbbb/a. Thus the letters are repeated twice, then thrice, then four times and so on.

17. _ nmmn _ mmnn _ mnnm _

A)nmmn

B)mnnm

C)nnmm

D)nmnm

Answer:C

Explanation:

The series is nnmm/nnmn/nnmm/nnmm. Thus, the pattern 'nnmm' is repeated.

18. a _ n _ b _ _ ncb _ _ ncb

A)abbbec

B)abebeb

C)bacbab

D)bcabab

Answer:D

Explanation:

The series is abncb/abncb/abncb. Thus, the pattern 'abncb' is repeated.

19. a _ ba _ b _ b _ a _ b

A)abaab

B)abbab

C)aabba

D)bbabb

Answer:D

Explanation:

The series is abb/abb/abb/abb. Thus, the pattern 'abb' is repeated.

20. cccbb _ aa _ cc _ bbbaa _ c

A)aebe

B)baca

C)baba

D)acba

Answer:B

Explanation:

The series is ccc bbb aaa/ccc bbb aaa/c. Thus, the pattern ccc bbb aaa is repeated.

21. bca _ b _ aabc __ a __ caa

A)acab

B)bcbb

C)cbab

D)ccab

Answer:A

Explanation:

The series is bcaa/bcaa/bcaa/bcaa. Thus, the pattern 'bcaa' is repeated.

22. ab __ d __ aaba __ na _ badna _ b

A)andaa

B)babda

C)badna

D)dbanb

Answer:A

Explanation:

The series is abadna/abadna/abadna/ab. Thus, the pattern 'abadna' is repeated.

23. m _ nm _ n _ an _ a _ ma _

A)aamnan

B)ammanm

C)aammnn

D)amammn

Answer:C

Explanation:

The series is man/man/man/man/man. Thus, the pattern 'man' is repeated.

24. _bcc _ ac _ aabb _ ab _ cc

A)aabca

B)abaca

C)bacab

D)bcaca

Answer:C

Explanation:

The series is bbccaa/ccaabb/aabbcc. Thus, the letter pairs move in a cyclic order.

25. _ op _ mo _ n _ _ pnmop _.

A)mnpmon

B)mpnmop

C)mnompn

D)mnpomn

Answer:A

Explanation:

The series is mopn/mopn/mopn/mopn. Thus, the pattern 'mopn' is repeated.

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.

Directions : In each of the following questions, various terms of an alphabet series are given with one or more terms missing. Choose the missing terms out of the given alternatives.

Letter series is easy to learn - You will enjoy it.