Coding Decoding Reasoning Questions and Answers for Competitive Exams – Tricks, Rules & Practice

Coding Decoding Reasoning Questions and Answers – Complete Notes, Tricks & Practice

Coding-Decoding is one of the most important Reasoning topics asked in competitive exams such as SSC, Railway, Banking, Police, Defence and other government exams. In these questions, letters, numbers, words or sentences are coded according to a specific pattern, and candidates have to identify the rule and find the correct answer. This complete Coding-Decoding Notes covers alphabet positions, letter shifting, reverse coding, opposite letters, number coding, word coding, sentence coding, important tricks, shortcuts, solved examples and practice questions to help you solve Coding-Decoding questions quickly and accurately.

Basic Concept

In coding-decoding questions, a word, letter, number, or sentence is changed according to a particular rule. The changed form is called its code.

You must know the English alphabet positions – MOST IMPORTANT 

Easy trick

• Remember: A B C D E = 1 2 3 4 5, Then continue normally.

EJOTY – Very Easy Trick

• EJOTY is a shortcut to remember the 5th, 10th, 15th, 20th and 25th letters of the alphabet. Each letter comes after 5 positions.

So, whenever you need to quickly find alphabet positions, use EJOTY as your checkpoints.

Example-1: Find the position of R

You know: O = 15

After O: 

P = 16, Q = 17 , R = 18

So R = 18.

Example-2: Find the position of W

You know:

T = 20

U = 21 ,V = 22, W = 23

So W = 23.

Reverse Alphabet Position

Sometimes the alphabet is counted from Z = 1.

FORMULA

For any letter:  Reverse position = 27 − Normal position

Example: Since, G = 7.  So, position of G in reverse condition = 27 − 7 = 20

Therefore, G = 20 in reverse alphabet.

• Opposite Letter Shortcut

The alphabet pairs are: A-Z, B-Y, C-X, D-W, E-V, F-U, G-T, H-S, I-R, J-Q, K-P, L-O, M-N

Solved Questions and Answer

Q1. In a certain code language, “SHORTER” is written as “UJQTVGT”. How will “BANARAS” be written in that code?

(a) DCPCTCU

(b) DPCCTCU

(c) DCPCCTU

(d) PCDCUCT

Solution:

First compare SHORTER → UJQTVGT

S → U (+2)

H → J (+2)

O → Q (+2)

R → T (+2)

T → V (+2)

E → G (+2)

R → T (+2)

Here every letter moves +2.

Similarly,

BANARAS

B → D (+2)

A → C (+2)

N → P (+2)

A → C (+2)

R → T (+2)

A → C (+2)

S → U (+2)

So, BANARAS = DCPCTCU

So, Answer : (a) DCPCTCU

Q2. In a certain code language, “STEAMER” is written as “TUFBNFS”. How will “HOUSE” be written in that code?

(a) IPVUF

(b) IPUTF

(c) IPVTF

(d) IPVSF

Solution:

First compare STEAMER → TUFBNFS

S → T (+1)

T → U (+1)

E → F (+1)

A → B (+1)

M → N (+1)

E → F (+1)

R → S (+1)

Here every letter moves +1.

Similarly,

HOUSE

H → I (+1)

O → P (+1)

U → V (+1)

S → T (+1)

E → F (+1)

So, HOUSE = IPVTF

So, Answer :  (c) IPVTF

Q3. In a certain code language, “MONKEY” is written as “XDJMNL”. How will “TIGER” be written in that code?

(a) QDHJS

(b) SDFHS

(c) SHFDQ

(d) QDFHS

Solution:

First compare MONKEY → XDJMNL

First, the word is written in reverse:

MONKEY → YEKNOM

Then each letter moves −1:

Y → X (−1)

E → D (−1)

K → J (−1)

N → M (−1)

O → N (−1)

M → L (−1)

Similarly,

First, the word is written in reverse:

TIGER → REGIT

Now, move each letter  −1:

R → Q (−1)

E → D (−1)

G → F (−1)

I → H (−1)

T → S (−1)

So, TIGER = QDFHS

So, Answer :  (d) QDFHS

Q4. In a certain code language, “AWAKE” is written as “ZVAJD”. How will “FRIEND” be written in that code?

(a) IQHDME

(b) EQHDEM

(c) EQHDME

(d) EQHDMC

Solution:

First compare AWAKE → ZVZJD

Every letter moves −1:

A → Z (−1)

W → V (−1)

A → Z (−1)

K → J (−1)

E → D (−1)

Similarly,

Move each letter −1:

FRIEND

F → E (−1)

R → Q (−1)

I → H (−1)

E → D (−1)

N → M (−1)

D → C (−1)

So, FRIEND = EQHDMC

So, Answer :  (d) EQHDMC

Q5. In a certain code language, “POLISH” is written as “MLIFPE”. How will “DIG” be written in that code?

(a) ZFD

(b) AFD

(c) BGD

(d) EHF

Solution:

First compare POLISH → MLIFPE

P → M ( −3 )

O → L ( −3 )

L → I ( −3 )

I → F ( −3 )

S → P ( −3 )

H → E ( −3 )

So, the rule is −3 for every letter.

Similarly,

Move each letter −3:

DIG:

D → A ( −3 )

I → F ( −3 )

G → D ( −3 )

Therefore:

DIG → AFD

So, Answer :  (b) AFD

Q6. In a certain code language, “CAT” is written as “DDY”. How will “BIG” be written in that code?

(a) CML

(b) CUL

(c) CLL

(d) CNL

Solution:

First compare CAT → DDY

  C → D ( +1)

A → D ( +3)

T → Y ( +5)

Here , The pattern is: +1, +3, +5

Similarly,

Now apply the same rule to BIG:

  B + 1 = C

I + 3 = L

G + 5 = L  

Therefore: BIG → CLL

Answer: (c) CLL

Q7. In a certain code language, “LOYAL” is written as “JOWAJ”. How will “PRONE” be written in that code?

(a) NRMNC

(b) QRPNF

(c) NRNMD

(d) QPNMF

Solution:

First compare LOYAL → JOWAJ

L → J (−2)

O → O (same)

Y → W (−2)

A → A (same)

L → J (−2)

So the rule is:  1st letter −2, 2nd letter same, 3rd letter −2, 4th letter same, 5th letter −2

Similarly,

Now apply the same rule to PRONE:

P → N (−2)

R → R (same)

O → M (−2)

N → N (same)

E → C (−2)

Therefore:

PRONE → NRMNC

Answer: (a) NRMNC

Q8. In a certain code language, “DOG” is written as “WTL”. How will “CAT” be written in that code?

 (a) XZG

(b) XYG

(c) XGZ

(d) XAZ

Solution:

First compare DOG →  WTL

D → W

O → L

G → T

Here, the reverse Letter is used , see The alphabet pairs : A-Z, B-Y, C-X, D-W, E-V, F-U, G-T, H-S, I-R, J-Q, K-P, L-O, M-N

But the question gives:

DOG → WTL

So, after finding the opposite letters, the last two letters are interchanged.

Similarly,

Now apply the same rule to CAT:

C → X

A → Z

T → G

Now interchange the last two letters:

X   Z G

     ↓ ↓

X  G Z

Therefore:  CAT = XGZ

Answer: (c) XGZ

Q9. If DELHI is coded as 73541 and CALCUTTA as 82589662, how will CALICUT be coded?

(a) 5279431

(b) 5978213

(c) 8251896

(d) 8543691

Solution:

Given , DELHI → 73541

We need to find the code of each letter.

D → 7

E → 3

L → 5

H → 4

I → 1

From: 

CALCUTTA → 82589662

C → 8

A → 2

L → 5

C → 8

U → 9

T → 6

T → 6

A → 2

From the above two words we get codes of each letters of CALICUT  as given below

C → 8

A → 2

L → 5

I → 1

C → 8

U → 9

T → 6

Therefore, CALICUT = 8251896

Answer: (c) 8251896

Q10. If the letters of PRABA are coded as 27595, and THILAK as 368451, how will BHARATHI be coded?

(a) 37536689

(b) 57686535

(c) 96575368

(d) 96855368

Solution:

Given , PRABA → 27595

We need to find the code of each letter.

P → 2

R → 7

A → 5

B → 9

From:

THILAK → 368451

T → 3

H → 6

I → 8

L → 4

A → 5

K → 1

From the above two words we get codes of each letters of BHARATHI  as given below

B → 9

H → 6

A → 5

R → 7

A → 5

T → 3

H → 6

I → 8

Therefore:  BHARATHI = 96575368

Answer: (c) 96575368

Q11. In a certain code, 15789 is written as XTZAL and 2346 is written as NPSU. How is 23549 written in that code?

(a) NPTUL

(b) PNTSL

(c) NPTSL

(d) NBTSL

Solution:

Given , 15789 → XTZAL

We need to Find the code of each number.

1 → X

5 → T

7 → Z

8 → A

9 → L

From:

2346 → NPSU

2 → N

3 → P

4 → S

6 → U

From the above two numbers we get codes of each numbers of 23549 as given below

2 → N

3 → P

5 → T

4 → S

9 → L

Therefore: 23549 = NPTSL

Answer: (c) NPTSL

Q12. If AT = 20, BAT = 40, then CAT = ?

(a) 80

(b) 60

(c) 45

(d) 90

Solution:

Given,  AT = 20

Alphabet positions:

A = 1

T = 20

Here: 1 × 20 = 20

Now:  BAT = 40

Alphabet positions:

B = 2

A = 1

T = 20

Therefore: 2 × 1 × 20 = 40

So the rule is:  Multiply the alphabet positions of all letters.

Similarly, 

For , CAT,  Alphabet positions:

C = 3

A = 1

T = 20

Therefore: 3 × 1 × 20 = 60

So, CAT = 60

Answer: (b) 60

Q13. If A = 1, B = 2, C = 3, ..., Z = 26, what is the value of “BAD”?

(a) 6

(b) 7

(c) 8

(d) 9

Solution:

Given , A = 1, B = 2, C = 3, ..., Z = 26

Now For BAD , Find the alphabet position of each letter:

B = 2

A = 1

D = 4

Adding  them: 2 + 1 + 4 = 7

Therefore: BAD = 7

Answer: (b) 7

Note:  Observing the options you have to guess which operation (+ , - , x etc) you need to solve

Q14. If CAT : DBU :: DOG : ?

(a) EPH

(b) FQI

(c) DPH

(d) EOG

Solution:

Given, CAT → DBU

C → D (+1)

A → B (+1)

T → U (+1)

Similarly, apply +1 to DOG:

D → E

O → P

G → H

Therefore: DOG → EPH

Answer: (a) EPH

Q15. If MANGO : OGNAM :: APPLE : ?

  (a) ELPPA

(b) ELPAP

(c) EPLPA

(d) LPPAE  

Solution:

Given, MANGO → OGNAM

The word is simply reversed.

M A N G O

↓ ↓ ↓ ↓ ↓

O G N A M

Now: 

A P P L E

↓ ↓ ↓ ↓ ↓

E L P P A

Therefore: APPLE → ELPPA

Answer: (a) ELPPA

Word-Based Sentence Coding

Q16. If orange is called butter, butter is called soap, soap is called ink, ink is called honey and honey is called orange, which of the following is used for washing clothes?

  (a) Honey

(b) Butter

(c) Orange

(d) Ink  

Solution:

According to the question:

Soap is called Ink.

So, the thing used for washing clothes is Ink in the given code language.

Answer: (d) Ink

Q17. If sky is called sea, sea is called water, water is called air, air is called cloud and cloud is called river, then which of the following is used for drinking?

(a) Sky

(b) Water

(c) Sea

(d) Air

Solution:

According to the question: 

Water is called Air.

Therefore, the coded name for the thing we drink is Air.

Answer: (d) Air

Q18. If water is called blue, blue is called red, red is called white, white is called sky, sky is called green and green is called rain, then which of the following is the colour of milk?

  (a) Air

(b) Green

(c) White

(d) Sky  

Solution:

According to the question: 

White is called Sky.

Therefore, in the given code language, the colour of milk is called Sky.

Answer: (d) Sky

Q19. If pen is called wood, wood is called fan, fan is called chair, and chair is called grass, then on which of the following will a person sit?

  (a) Fan

(b) Wood

(c) Chair

(d) Grass  

Solution:

According to the question: 

Chair is called Grass.

Therefore, in the code language, a person will sit on Grass.

Answer: (d) Grass

Q20. In a certain code, “bie nie pie” means “some good jokes”, “nie bat lie” means “some real stories”, and “pie lik tol” means “many good stories”. Which word in that code means “jokes”?

  (a) bie

(b) pie

(c) nie

(d) None of the above  

Solution:

We have:

1. bie nie pie = some good jokes

2. nie bat lie = some real stories

3. pie lik tol = many good stories

Let's Compare Sentence 1 and Sentence 2:

1. bie nie pie = some good jokes 

2.  nie bat lie = some real stories

Here, Common code = nie

And Common word in the meanings: some

Therefore: nie = some

Again, Compare Sentence 1 and Sentence 3:

1. bie nie pie = some good jokes

3. pie lik tol = many good stories

Here, Common code = pie

And Common word in the meaning: good

Therefore: pie = good

Now look at Sentence 1:

1. bie nie pie = some good jokes

We already know:

nie = some

pie = good

So the remaining code bie must mean jokes.

Therefore: Answer: (a) bie

Q21. If in a certain language, “oka peru” means “fine cloth”, “meta lisa” means “clear water” and “dona lisa peru” means “fine clear weather”, then which word in that language means “weather”?  

  (a) peru

(b) oka

(c) meta

(d) dona

Solution:

We have:

1. oka peru = fine cloth

2. meta lisa = clear water

3. dona lisa peru = fine clear weather

Let's Compare Sentence 1 and Sentence 3:

1. oka peru = fine cloth

3. dona lisa peru = fine clear weather

The common word in both codes is: peru

And the common word in both meanings is: fine

Therefore: peru = fine

Again, Compare Sentence 2 and Sentence 3:

2. meta lisa = clear water

3. dona lisa peru = fine clear weather

The common code is: lisa

  And the common word in both meanings is: clear

Therefore: lisa = clear

Now look at Sentence 3:

3. dona lisa peru = fine clear weather

We already know:

peru = fine

lisa = clear

So the remaining word:

dona = weather

Therefore: Answer: (d) dona

Q22. In a certain code, “37” means “which class” and “583” means “caste and class”. What is the code for “caste”?

  (a) 3

(b) 7

(c) 8

(d) Either 5 or 8

Solution:

We have:

37 = which class

583 = caste and class

The common word between the two meanings is: class

  The common number between the two codes is:  3

Therefore: 3 = class

Now look at:

583 = caste and class

So "caste" can be represented by 5 or 8.

Or "and" can be represented by 5 or 8.

Therefore: Answer: (d) Either 5 or 8

Practice Questions

Q1. If DOG : EPH :: CAT : ?

(a) DBU

(b) ECV

(c) BZS

(d) DCT

Q2. If BAT : YZG :: DOG : ?

(a) WLT

(b) XMT

(c) WLG

(d) VKS

Q3. If RAM : SBN :: SUN : ?

(a) TVO

(b) TUN

(c) SVP

(d) UVO

Q4. If PEN : QFO :: BOOK : ?

(a) CPPL

(b) CPNL

(c) BPPK

(d) DQQM

Q5. If LION : MJPO :: TIGER : ?

(a) UJHFS

(b) UJGER

(c) SHFDQ

(d) VJHFS

Q6. If COLD : XLOW :: WARM : ?

(a) DZIN

(b) DZIN

(c) DZIN

(d) DZRM

Q1.  Answer: (a) DBU  

Q2. Answer: (a) WLT  

Q3. Answer: (a) TVO  

Q4. Answer: (a) CPPL  

Q5. Answer: (a) UJHFS  

Q6. Answer: (a) DZIN

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FAQs

Q1. What is Coding-Decoding in Reasoning?

Ans: Coding-Decoding is a reasoning topic where letters, numbers, words or sentences are changed according to a particular rule. You have to identify the rule and apply it to find the correct answer.

Q2. What are the main types of Coding-Decoding questions?

Ans: The common types include letter shifting, reverse coding, opposite-letter coding, number coding, word coding, sentence coding, substitution coding and mixed coding.

Q3. What is the alphabet position of A to Z?

Ans: A = 1, B = 2, C = 3, ... and Z = 26.

Q4. What is the EJOTY trick?

Ans: EJOTY helps remember every 5th letter of the alphabet:

E = 5, J = 10, O = 15, T = 20, Y = 25.

Q5. How can I find the opposite letter of an alphabet?

Ans: Use the formula:

Opposite position = 27 − original position

For example, C = 3, so 27 − 3 = 24. The 24th letter is X. Therefore, C ↔ X.

Q6. How do I solve sentence Coding-Decoding questions?

Ans: Compare the given sentences and find common words and common codes. A common word generally has a common code.

Q7. What is Coding-Decoding analogy?

Ans: In analogy questions, you identify the relationship between the first pair and apply the same rule to the second pair.

Example:

CAT : DBU :: DOG : EPH

Here, every letter moves +1.