Coding Decoding Reasoning Questions – Practice MCQ

Coding-Decoding Reasoning Questions –Coding-Decoding is a critical component of logical reasoning in competitive exams like SBI Clerk, SBI PO, IBPS, SSC, and others. These questions evaluate a candidate’s ability to identify and apply patterns to encode or decode information. They test logical reasoning, pattern recognition, and quick problem-solving, skills essential for analytical roles in banking and other sectors.

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What is Coding-Decoding?

Coding transforms a word, number, or phrase into a different form using a specific rule (e.g., shifting letters, replacing digits, or substituting symbols). Decoding involves reversing the process to retrieve the original information. The key challenge is identifying the rule, which may involve letter shifts, numerical transformations, word substitutions, or conditional logic.

Types of Coding Decoding Reasoning Questions

• Letter Coding: Letters are shifted or replaced based on their alphabetical positions or a specific pattern. Example: If 'CAT' is coded as 'EDW', each letter is shifted forward (C+2=E, A+3=D, T+3=W).
• Number Coding: Letters or words are represented by numbers, often based on their alphabetical order or a custom rule. Example: If 'A=1, B=2, ..., Z=26', 'BAD' becomes '214'.
• Mixed Coding: Combines letters, numbers, and symbols with complex or varying rules. Example: 'MANGO' coded as 'OZTKF' involves varying shifts for each letter.
• Word Coding: Entire words are replaced with other words or codes. Example: If 'pen' is coded as 'book', 'ink' as 'paper', then 'pen ink' becomes 'book paper'.
• Substitution Coding: Specific letters, numbers, or symbols are substituted with others (e.g., vowels replaced with a symbol). Example: If vowels are replaced with '@', 'CAT' becomes 'C@T'.
• Conditional Coding: The coding rule depends on conditions, such as the position or nature of the word (e.g., vowel or consonant). Example: If the first letter is a vowel, add 1 to each letter’s position; otherwise, subtract 1.

Steps to Solve Coding-Decoding Questions

1. Identify the Pattern: Compare the input and coded output to detect shifts, replacements, or transformations.
2. Check Positions: Determine if the rule varies by position (e.g., first letter vs. last letter).
3. Test the Rule: Apply the pattern to given examples to ensure consistency.
4. Apply to the Question: Use the rule to encode or decode the required term.
5. Verify Variations: Watch for conditional rules, reverse patterns, or alternating shifts.

Tips for Success

• Memorize the alphabet with positions (A=1 to Z=26) for quick reference.
• Look for common patterns like +1 or +2 shifts in letter coding.
• Use elimination in multiple-choice questions to narrow down options.
• Practice diverse question types to build familiarity with different patterns.
• Manage time effectively, as complex rules can be time-consuming.

Common Mistakes to Avoid

• Misinterpreting shift directions (e.g., forward vs. backward).
• Missing conditional or position-specific rules.
• Failing to verify the pattern across all examples.
• Confusing similar codes (e.g., mistaking 'I' for 'J').

Coding Decoding Reasoning Questions are a scoring opportunity in competitive exams if approached systematically. By understanding the types, practicing regularly, and applying logical steps, candidates can improve accuracy and speed. Consistent practice with varied problems will help master this topic and boost overall reasoning performance.

1000 Coding Decoding Reasoning Questions with PDF

Practice Coding Decoding Questions with Answers

1. Letter Coding

Question 1: If 'DOG' is coded as 'GQI', how is 'CAT' coded?

A) FJW B) IKF C) EDW D) GHY

Answer: C) EDW

Explanation: DOG → GQI: D(4)→G(7): +3, O(15)→Q(17): +2, G(7)→I(9): +2. Pattern: +3, +2, +2. Apply to CAT: C(3)→E(5): +2, A(1)→D(4): +3, T(20)→W(23): +3. Code: EDW.

Question 2: If 'PEN' is coded as 'QFO', how is 'INK' coded?

A) JOL B) KPM C) IOK D) JNL

Answer: A) JOL

Explanation: PEN → QFO: P(16)→Q(17): +1, E(5)→F(6): +1, N(14)→O(15): +1. Pattern: +1 to each letter. Apply to INK: I(9)→J(10), N(14)→O(15), K(11)→L(12). Code: JOL.

Question 3: If 'SUN' is coded as 'UVQ', how is 'MOON' coded?

A) OQRQ B) PQSP C) NPPP D) ORQQ

Answer: B) PQSP

Explanation: SUN → UVQ: S(19)→U(21): +2, U(21)→V(22): +1, N(14)→Q(17): +3. Pattern: +2, +1, +3. Apply to MOON: M(13)→P(16): +3, O(15)→Q(17): +2, O(15)→S(18): +3, N(14)→P(16): +2. Code: PQSP.

Question 4: If 'FISH' is coded as 'EJTK', how is 'BIRD' coded?

A) AKUF B) CJVG C) DKWH D) ELXI

Answer: A) AKUF

Explanation: FISH → EJTK: F(6)→E(5): -1, I(9)→J(10): +1, S(19)→T(20): +1, H(8)→K(11): +3. Pattern: -1, +1, +1, +3. Apply to BIRD: B(2)→A(1): -1, I(9)→K(11): +2, R(18)→U(21): +3, D(4)→F(6): +2. Code: AKUF.

Question 5: If 'BALL' is coded as 'CZOO', how is 'FALL' coded?

A) IZOO B) JBOO C) KCPP D) ICPP

Answer: A) IZOO

Explanation: BALL → CZOO: B(2)→C(3): +1, A(1)→Z(26): +25 (or -1 in reverse), L(12)→O(15): +3, L(12)→O(15): +3. Pattern: +1, -1, +3, +3. Apply to FALL: F(6)→I(9): +3, A(1)→Z(26): -1, L(12)→O(15): +3, L(12)→O(15): +3. Code: IZOO.

2. Number Coding

Question 1: If each letter is coded by its alphabetical position (A=1, B=2, ..., Z=26), what is the code for 'WIND'?

A) 23-9-14-4 B) 22-9-14-4 C) 23-10-14-4 D) 23-9-15-4

Answer: A) 23-9-14-4

Explanation: W=23, I=9, N=14, D=4. Code: 23-9-14-4.

Question 2: If each letter is coded by its reverse alphabetical position (Z=1, Y=2, ..., A=26), what is the code for 'CAT'?

A) 24-26-23 B) 23-26-24 C) 24-23-26 D) 23-24-26

Answer: A) 24-26-23

Explanation: Reverse: Z=1, ..., A=26. C=24, A=26, T=23. Code: 24-26-23.

Question 3: If each letter is coded as its alphabetical position plus 1, what is the code for 'BAD'?

A) 2-1-4 B) 3-2-5 C) 2-2-4 D) 3-1-5

Answer: B) 3-2-5

Explanation: B=2→3 (+1), A=1→2 (+1), D=4→5 (+1). Code: 3-2-5.

Question 4: If each letter’s alphabetical position is doubled (A=2, B=4, ..., Z=52), what is the code for 'KEY’?

A) 20-5-25 B) 20-10-50 C) 10-5-25 D) 20-10-25

Answer: B) 20-10-50

Explanation: K=11→22, E=5→10, Y=25→50. Code: 20-10-50.

Question 5: If each letter is coded as its alphabetical position minus its position in the word, what is the code for 'DOG’?

A) 3-14-6 B) 4-15-7 C) 3-13-5 D) 4-14-6

Answer: C) 3-13-5

Explanation: D=4 (1st, -1)→3, O=15 (2nd, -2)→13, G=7 (3rd, -3)→4. Code: 3-13-5.

3. Mixed Coding

Question 1: If 'STAR' is coded as 'UV@#', how is 'MOON' coded?

A) PQ@# B) OP@# C) PQ#$ D) OQ@#

Answer: A) PQ@#

Explanation: STAR → UV@#: S(19)→U(21): +2, T(20)→V(22): +2, A→@, R→#. Pattern: +2, +2, vowel→@, consonant→#. Apply to MOON: M(13)→P(16): +3, O(15)→Q(17): +2, O→@, N→#. Code: PQ@#.

Question 2: If 'BOOK' is coded as '2PPL', how is 'READ' coded?

A) 2FBE B) 1FBE C) 2EBF D) 1EBF

Answer: A) 2FBE

Explanation: BOOK → 2PPL: B(2)→2 (count vowels: 2), O(15)→P(16): +1, O(15)→P(16): +1, K(11)→L(12): +1. Pattern: Vowel count, +1, +1, +1. READ: 2 vowels→2, R(18)→S(19): +1, E(5)→F(6): +1, A(1)→B(2): +1. Code: 2FBE.

Question 3: If 'MANGO' is coded as 'OZTKF', how is 'LEMON' coded?

A) FJHLTK B) SGYAF C) RNZBG D) QMYAF

Answer: C) RNZBG

Explanation: MANGO → OZTKF: M(13)→O(15): +2, A(1)→Z(26): -2, N(14)→T(20): +6, G(7)→K(11): +4, O(15)→F(6): -9. Apply to LEMON: L(12)→R(18): +6, E(5)→N(14): +9, M(13)→Z(26): +13, O(15)→B(2): -13, N(14)→G(7): -7. Code: RNZBG.

Question 4: If 'FAN' is coded as '1$J', how is 'GAP' coded?

A) 1$I B) 2$I C) 1$J D) 2$J

Answer: A) 1$I

Explanation: FAN → 1$J: F(6)→1 (vowel count: 1), A→$, N(14)→J(10): -4. Pattern: Vowel count, vowel→$, last letter-4. GAP: 1 vowel→1, A→$, P(16)→I(9): -7. Code: 1$I.

Question 5: If 'HAT' is coded as 'J3W', how is 'PEN' coded?

A) R2Q B) Q3Q C) R3Q D) Q2Q

Answer: C) R3Q

Explanation: HAT → J3W: H(8)→J(10): +2, A (1 vowel→3: position 2), T(20)→W(23): +3. Pattern: +2, vowel count at pos 2, +3. PEN: P(16)→R(18): +2, 1 vowel→3, N(14)→Q(17): +3. Code: R3Q.

4. Word Coding

Question 1: If 'run' is coded as 'jump', 'sit' as 'stand', and 'walk' as 'move', what is the code for 'run sit walk'?

A) jump stand move B) move jump stand C) stand jump move D) jump move stand

Answer: A) jump stand move

Explanation: run→jump, sit→stand, walk→move. For 'run sit walk': run→jump, sit→stand, walk→move. Code: jump stand move.

Question 2: If 'book' is coded as 'pen', 'pen' as 'ink', and 'ink' as 'paper', what is the code for 'pen book ink'?

A) ink pen paper B) paper ink pen C) pen ink paper D) ink paper pen

Answer: A) ink pen paper

Explanation: pen→ink, book→pen, ink→paper. For 'pen book ink': pen→ink, book→pen, ink→paper. Code: ink pen paper.

Question 3: If 'cat' is coded as 'dog', 'dog' as 'rat', and 'rat' as 'bat', what is the code for 'dog cat’?

A) rat dog B) bat rat C) dog bat D) rat bat

Answer: A) rat dog

Explanation: dog→rat, cat→dog. For 'dog cat': dog→rat, cat→dog. Code: rat dog.

Question 4: If 'sky' is coded as 'blue', 'cloud' as 'white', and 'run' as 'yellow', what is the code for 'sun sky cloud’?

A) yellow blue white B) blue yellow white C) white blue yellow D) yellow white blue

Answer: A) yellow blue white

Explanation: sun→yellow, sky→blue, cloud→white. For 'sun sky cloud': sun→yellow, sky→blue, cloud→white. Code: yellow blue white.

Question 5: If 'tree' is coded as 'leaf', 'flower' as 'petal', and 'root' as 'stem', what is the code for 'flower root tree’?

A) petal stem leaf B) leaf petal stem C) stem leaf petal D) petal leaf stem

Answer: A) petal stem leaf

Explanation: flower→petal, root→stem, tree→leaf. For 'flower root tree': flower→petal, root→stem, tree→leaf. Code: petal stem leaf.

5. Substitution Coding

Question 1: If all vowels are replaced with '@', how is 'TRAIN' coded?

A) TR@@N B) TR@N C) T@@N D) @R@N

Answer: B) TR@N

Explanation: Vowels (A, E, I, O, U). In 'TRAIN', I is the only vowel. Replace I with '@'. Code: TR@N.

Question 2: If all consonants are replaced with '#', how is 'BOOK' coded?

A) #OO# B) #O#K C) B#O# D) #OOK

Answer: A) #OO#

Explanation: Consonants: B, K. Replace B and K with '#'. Code: #OO#.

Question 3: If the first and last letters are swapped, how is 'FANS' coded?

A) SANF B) AFNS C) SNAF D) NFAS

Answer: A) SANF

Explanation: Swap first (F) and last (S). Code: SANF.

Question 4: If each letter is replaced with the next letter in the alphabet, how is 'WIND' coded?

A) XJOE B) YKPF C) XINE D) YJOE

Answer: A) XJOE

Explanation: W(23)→X(24), I(9)→J(10), N(14)→O(15), D(4)→E(5). Code: XJOE.

Question 5: If all letters are replaced with their reverse alphabetical counterparts (A↔Z, B↔Y, ..., Z↔A), how is 'STAR' coded?

A) HGZI B) IHZJ C) JIAK D) IGYH

Answer: A) HGZI

Explanation: S↔I (19↔9), T↔I (20↔8), A↔Z (1↔26), R↔I (18↔9). Code: HGZI.

6. Conditional Coding

Question 1: If the first letter is a vowel, add 1 to each letter’s position; otherwise, subtract 1. How is 'APPLE' coded?

A) BQQMF B) ZOOKD C) BPPLF D) ZNNJD

Answer: A) BQQMF

Explanation: First letter A (vowel), so +1. A(1)→B(2), P(16)→Q(17), P(16)→Q(17), L(12)→M(13), E(5)→F(6). Code: BQQMF.

Question 2: If the word has an even number of letters, reverse the word; otherwise, shift each letter +1. How is 'FAN' coded?

A) GBO B) NAF C) OBG D) AFN

Answer: A) GBO

Explanation: FAN: 3 letters (odd), so +1. F(6)→G(7), A(1)→B(2), N(14)→O(15). Code: GBO.

Question 3: If the last letter is a consonant, add 2 to each letter; otherwise, subtract 2. How is 'WAVE' coded?

A) UZCC B) YXGG C) UYCC D) YZGG

Answer: A) UZCC

Explanation: Last letter E (vowel), so -2. W(23)→U(21), A(1)→Z(26-1=25), V(22)→T(20), E(5)→C(3). Code: UZCC.

Question 4: If the word starts with a consonant, swap the first and last letters; otherwise, add 1 to each letter. How is 'KING' coded?

A) GNJK B) LJOH C) JOHL D) GNIK

Answer: A) GNJK

Explanation: First letter K (consonant), so swap first (K) and last (G). KING→GNIK. Code: GNJK.

Question 5: If the word has more than 3 letters, add 3 to each letter; otherwise, subtract 3. How is 'SUN' coded?

A) PRK B) VXQ C) QSL D) UYO

Answer: A) PRK

Explanation: SUN: 3 letters, so -3. S(19)→P(16), U(21)→R(18), N(14)→K(11). Code: PRK.