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
I) 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, ___
a) R b) T c) Q d) S
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.
Answer: a
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: What is the next letter in the series CM, DN, EO, FP, __
a) GR b) GQ c) HQ d) HR
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.
Answer: b
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, ___
a) XDY b) YFZ c) YFA d) XFY
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.
Answer: b
II) 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.
Example: _ stt _ tt _ tts _
a) tsts b) ttst c) sstt d) tsst
Explanation: The series is tst/ tst/ tst/ tst. Thus, the pattern 'tst' is repeated.
Answer: d
III) 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: A series is given with one term missing. Select the correct alternative from the given ones that will complete the series.
C11, V17, O23, ___
a) H30 b) H31 c) I29 d) I31
Explanation: Letter Series difference with -6
2nd is a Number series of prime number with one gap
Answer: b
Model Questions
1. A series is given, with one term missing. Choose the correct alternative from the given ones that will complete the series.
AbCdE, DeFgH, GhIjK, JkLmN, ?
a) OpQrS b) NoPqR
c) MnOpQ d) LmNoP
Explanation: AbCdE, DeFgH, GhIjK, JkLmN, ?
−1 −1 −1
Remaining all are +3 series
Answer: c
2. In the following question, which one set of letters when sequentially placed at the gaps in the given letter series shall complete it?
_ yzaa _ y _ xy _ aazy _
a) xxzzx b) xxaza c) xzxzx d) aazzx
Explanation: xyzaazyx/ xyzaazyx
xyzaazyx series is repeating
Answer: c
3. A series is given with one term missing. Select the correct alternative from the given ones that will complete the series.
A, C, E, G, ?
a) H b) I c) J d) F
Explanation: +2 series
Answer: b
4. A series is given with one term missing. Select the correct alternative from the given ones that will complete the series.
KV, LU, MT, ?
a) NS b) OS c) OU d) SN
Explanation: +1, −1 series
Answer: a
5. A series is given, with one term missing. Choose the correct alternative from the given ones that will complete the series.
L, N, Q, S, V, ?
a) W b) Y c) Z d) X
Explanation: Here we have add the series of
+2 and +3 in the given series. so, V + 2 = X.
Answer: d
6. In the following question, which one set of letters when sequentially placed at the gaps in the given letter series shall complete it?
efg _ _ eff _ ghhe _ eff _ gggh _ h
a) eghhfe b) ghhhh c) hegefh d) hgefhe
Explanation:
efgh/ eeffgghh/ eeefffggghhh
Answer: c
7. A series is given with one term missing. Select the correct alternative from the given ones that will complete the series.
AK12, GV29, LF18, PO?
a) 34 b) 31 c) 42 d) 40
Explanation: AK 12 = 1 + 11 = 12
GV 29 = 7 + 22 = 29
LF 18 = 12 + 6 = 18
PO _ = 16 + 15 = 31
Answer: b
8. In the following question, which one set of letters when sequentially placed at the gaps in the given letter series shall complete it?
I m _ o _ n m _ I _ n _ _ n m I
a) moInon b) noImoo
c) nomIoo d) nooImm
Explanation: Imno/ onmI/ Imno/ onmI
Answer: b
9. A series is given with one term missing. Select the correct alternative from the given ones that will complete the series.
BT, DR, FP, ?
a) HO b) HN c) NH d) OH
Explanation: Series of +2 and −2
Answer: b
10. A series is given with one term missing. Select the correct alternative from the given ones that will complete the series.
AG, LR, WC, HN, ?
a) QY b) RX c) SY d) TZ
Explanation: A +11 L +11 W +11 H +11 S
G +11 R +11 C +11 N +11 Y
Answer: c
11. In the following question, which one set of letters when sequentially placed at the gaps in the given letter series shall complete it?
a _ bc _ a _ bcdabc _ da _ cd _
a) acbddb b) adbcbd
c) cabddc d) ddcbbc
Explanation:
a a b c d / a b b c d / a b c c d / a b c d d
Answer: b
12. A series is given with one term missing. Select the correct alternative from the given ones that will complete the series.
FK27, LQ64, RW125, ?
a) CX216 b) XB216
c) XC216 d) YB343
Explanation: F +6 L +6 R +6 X
K +6 Q +6 W +6 C
27 = 32, 64 = 42, 125 = 52, 216 = 62
Answer: c
13. A series is given with one term missing. Select the correct alternative from the given ones that will complete the series.
ACE, FHJ, KMO, ?
a) QRS b) PRT c) PRU d) QRV
Explanation: A + 2 = C + 2 = E + 1 = F
F + 2 = H + 2 = J + 1 = K
K + 2 = M + 2 = O + 1 = P
P + 2 = R + 2 = T
so PRT is comes next in series.
Answer: b
14. A series is given with one term missing. Select the correct alternative from the given ones that will complete the series.
CEG, IKM, OQS, ?
a) UWY b) UYX c) UVY d) TWY
Explanation: +6 Series
Answer: a
15. A series is given with one term missing. Select the correct alternative from the given ones that will complete the series.
LOQ, SVX, ZCE, ?
a) GJL b) GLJ c) GTL d) JLG
Explanation: +7 Series
Answer: a
16. A series is given with one term missing. Select the correct alternative from the given ones that will complete the series.
A, C, F, H, K, ?
a) M b) N c) L d) O
Explanation: Series of +2, +3
Answer: a
17. A series is given, with one term missing. Choose the correct alternative from the given ones that will complete the series.
XX, XOX, XXXX, XXOXX, XXXXXX, ?
a) XXXOXXXX b) XXXOXXX
c) XXXXXXX d) XXXOXXXO
Explanation: O comes as the middle value in the terms whenever the term has odd number of characters. The number of X in a term is also equal to the number of X in the previous term. Hence option b is the answer.
Answer: b
18. A series is given, with one term missing. Choose the correct alternative from the given ones that will complete the series.
DEC, HIG, LMK, PQO, TUS, ?
a) XYZ b) WXY c) XYW d) YZA
Explanation: +1, −2 Series Answer: c
19. A series is given, with one term missing. Choose the correct alternative from the given ones that will complete the series.
ZYX, VUT, QPO, MLK, HGF, ?
a) DCB b) CBA c) BCD d) EDC
Explanation: Difference of first place: −4, −4, −4
second place: −5, −5, −5 and
third place: −4, −4, −4
Answer: a
SOLVED EXAMPLES
1. What will come in the place of the question mark (?) in the following sequence?
CONSEQUENCES ONSEQUENCE NSEQUENC ? EQUE
(1) SEQUE (2) EQUEN (3) SEQUENC (4) SEQUEN (5) NONE OF THESE
Sol. (4)
2. What should come in place of the question mark (?) in the following series?
AC FH KM PR ?
(1) UW (2) VX (3) VW (4) TV (5) None of these
Sol. (1)
3. What will come in the place of the question mark (?) in the following sequence?
AI, BJ, CK, ?
(1) DL (2) DM (3) GH (4) LM (5) None of these
Sol. (1)
4. What will come in place of the question mark(?) in the following series of English alphabet?
AE CG EI GK ?
(1) MI (2) M (3) HM (4) IL (5) None of these
Sol. (2)
Example 5:
Which of the following will come in place of the question mark (?) In the alpha order given below?
AB ABC BC BCD CD CD ?
(1) D (2) E (3) C (4) F (5) None of these
Sol. (2) AB, ABC
BC, BCD
CD, CDE
EXERCISE-1
1. What will come next in the following letter series? AACACEACEGACEGIACEGI
A: K
Sol.
2. What will com …. E of question mark (?) in the alpha order given below? CBAACBAABCBAABCCBAAB?
A: C
Sol.
3. The following groups of alphabets form a certain pattern with regard to their positions in the English alphabetic series. Based upon the pattern, which of the following five alternatives shall replace the question mark? AD, FC, HK, MJ, ?
A: OR
Sol
4. Find the next term in the series T, R, P, N, L, ?, ?
A: J, H
Sol.
5. What will come next in the following series?
Ababcdbcdabcdedabcdefabed
A: c
Sol.
6. What should come next in the following letter series?
AABABCABCDANBDABCDEABCDEF
A: G
Sol.
7. Find the next term in the series AZ, GT, MN, ?, YB
A: SH
Sol.
8. Find the next term in the series GH, JL, NQ, SW, YD, ?
A: FL
Sol.
9. What should come next in the following letter series?
HGFEDCBABHGFEDCBAHFEDCBAH
Sol. HGFEDCBAH; GFEDCBAH; FEDCBAH; ed.........7.......
10. Find the next term in the series BMX, DNW, FOU, ?
A: HPT
Sol.
EXERCISE-2
Directions (Qs. 1 - 6): Find the missing term in the series.
1. BL, FP, JT, ___ , RB, VF
a) MW b) NX c) OY d) MX
Ans: b
2. BD, GI, LN, QS, ___
a) TV b) UW c) VX d) WY
Sol:
Ans: c
3. ND, IY, DT, YO, TJ, ___
a) MP b) NQ c) OF d) OE
Ans: d
4. DKY, FJW, HIU, JHS, ___
a) KGR b) LFQ c) KFR d) LGQ
Sol:
Ans: d
5. EAC, GCE, IEG, ___
a) JHI b) JGI c) KGI d) KHI
Sol:
Ans: c
6. CDF, DEG, EFH, ___
a) FGI b) FGH c) FHG d) EFI
Sol:
Ans: a
Directions (Qs. 7 - 10): In each of the letter series given below, some letters are missing which are given in that order as one of the four alternatives under it. Find the correct alternative in each case.
7. b _ _ b _ a b c _ b _ a
a) baaab b) cacac c) cbaac d) baacb
Sol: Here the series is bca ¾, bc¾a, bca¾, bc¾a.
Ans: b
8. a b _ _ b a a _ b _ _ a a b
a) aaaaa b) aacaa c) cccaa d) ccccc
Sol: Here the series is ab, aa ¾b, aaa¾b, a¾aaab.
Ans: a
9. a _ b a b _ b _ a b _ _ b a b
a) ccbbb b) babab c) bccca d) aabca
Sol: Here the series is ab¾bab, a¾bb¾ab, a¾bbab.
Ans: b
10. a _ _ a _ b a b _ a _ b
a) bbbbb b) babab c) bbaab d) aabaa
Sol: Here the series is abb ¾, ab¾b, abb¾, ab¾b.
Ans: a
Directions (Qs. 11 - 16): Find the missing term in the series.
11. EJO, TYD, INS, XCH, ___
a) NRW b) MRW c) MSX d) NSX
Sol:
Ans: c
12. P3C, R5F, T8I, V12L, ___
a) Y17O b) X17M c) X17O d) X16O
Sol:
Ans: c
13. DEB, IJG, NOL, ___ , XYV
a) RSP b) STP c) RSQ d) STQ
Sol:
Ans: d
14. PRT, ___ , BDF, HJL, NPR
a) UWY b) VYA c) VXZ d) UXW
Sol:
Ans: c
15. VWU, ZAY, ___, KLJ, RSQ
a) CDB b) DEC c) EFD d) GHF
Sol:
Ans: c
16. VER, RIV, ___, FUH, ZAN
a) LMN b) MNA c) MOC d) LOB
Sol:
Ans: d
Directions (Qs. 17 - 20): In each of the letter series given below, some letters are missing which are given in that order as one of the given alternatives under it. Find the correct alternative in each case.
17. _ bb _ a _ aba _ ba _ ba _
a) a b a b a b b) a a b b a b
c) a a a b b b d) b a a b a b
e) a a b a a b
Sol: When we put the letters given in choice (b) in the blanks, we get:
Here ‘abba’ and ‘abab’ alternatively repeat.
Ans: b
18. a _ cb _ ac _ b _ bc _ ca _ ab
a) a b c a b c b) a b c b c a
c) b c a a b c d) b c a b c a
e) b c b a b c
Sol: On filling in the blanks with the letters given in choice (c), we get the following.
Here ‘abc’, ‘bca’ and ‘cab’ repeat themselves in the sequence.
Ans: c
19. c _ m a g _ m _ s m c d _ _
a) m m g m s b) d s s d a
c) s s g s s d) d s g m a
e) m m g m a
Sol: After filling in the letters of choice (d), we get
Ans: d
20. _ CD _ GH _ KL _ _ P
a) BEIMN b) CDKLP
c) BFJMN d) BFINO
e) BEJMN
Sol: This is a series of consonants i.e., the vowels are omitted.
Ans: c
Alphabet Based Puzzles
1. In the following letter series how many times do PQR occur in that order?
Q M P N P Q R R O P Q N O P P Q R P M Q R O P Q R P P R R P Q R P
a) 5 b) 6 c) 4 d) 3
Ans: c
2. From the given alternatives, select the word which cannot be formed using the letters of the given word.
CONSTITUTIONAL
a) CONSULT b) LOCATION
c) TUTION d) TALENT
Sol: E is not found in word ‘CONSTITUTIONAL’ to make ‘TALENT’.
Ans: d
3. In the following list of English alphabets, one alphabet has not been used. Identify the same.
X N F A P S R W L T M D E X M G B C X Q J L O P V R C Q J Z O H S G O D I P T S M R A B E F G N U N E Y
a) V b) I c) K d) J
Sol: K is not used.
Ans: c
4. If alphabets are serially numbered, one of the answers given below has a meaningful word hidden in it. Identify the answer.
a) 5, 18, 5, 8, 1, 3, 5, 20 b) 5, 1, 3, 5, 20, 8, 18
c) 20, 5, 1, 3, 8, 5, 18 d) 20, 5, 8, 1, 3, 5, 18
Sol: T E A C H E R
20 5 1 3 8 5 18
Ans: c
5. From the given alternative words, select the word which can be formed using the letters of the given word.
DETERMINATION
a) DECLARATION b) NATIONAL
c) TERMINATED d) DEVIATION
Sol: Only TERMINATED can be made using letters of the given word.
Ans: c
Previous Questions (SSC-CGL 2017)
1. A series is given, with one term missing. Choose the correct alternative from the given ones that will complete the series. U, T, R, O, K, ?
a) G b) H c) E d) F
2. A series is given with one term missing. Select the correct alternative from the given ones that will complete the series. BCF, CDG, DEH, ?
a) EFI b) EFG c) DFI d) EGI
3. A series is given, with one term missing. Choose the correct alternative from the given ones that will complete the series. BCD, EFG, IJK, NOP, TUV, ?
a) YZZ b) ZZB c) BCD d) ABC
4. A series is given with one term missing. Select the correct alternative from the given ones that will complete the series. PNR, RQV, TTZ, ?, XZH
a) VWB b) UXC c) VWD d) UXE
5. In the following question, which one set of letters when sequentially placed at the gaps in the given letter series shall complete it? a _ c a a b _ a _ b c a a b _ a _ b _ a
a) cbacba b) bcacac c) acbaca d) bbacaa
Key: 1-d 2-a 3-d 4-c 5-b
