Coding-Decoding Questions and Answers for Competitive Exams

Coding-Decoding Questions and Answers for Competitive Exams

Coding-Decoding – Complete Notes for Competitive Exams

Introduction

Coding-Decoding is a key topic in the Reasoning Ability section** of competitive exams** like SSC, Banking, Railway, Defence, and State Exams.

It tests a candidate’s ability to:

  • Recognize patterns
  • Identify relationships between letters, numbers, or words
  • Decode or encode messages logically

Types of Coding-Decoding Questions

1. Letter Coding

  • Each letter in a word is replaced by another letter according to a pattern.
    Example: If CAT → DBU, then DOG → ?

2. Number Coding

  • Each word or letter is assigned a number based on a pattern.
    Example: if CAT = 312, DOG = ?

3. Symbol Coding

  • Letters or numbers are replaced with symbols or signs.
    Example: if A → @, B → #, C → %, then CAB → ?

4. Mixed Coding

  • Combination of letters, numbers, and symbols.
    Example: WORD → 2314, find code for DRAW.

5. Substitution Coding

  • Words are replaced with another word in a sentence using a specific rule.

6. Sequential Coding

  • Letters or numbers are shifted by a fixed sequence.
    Example: A → D, B → E, etc.

Short Tricks for Coding-Decoding

  • 🔤 Check the first and last letters for a pattern
  • ➕ Look for alphabetical shifts (+1, -2, etc.)
  • 🔢 For numbers, check addition, subtraction, or multiplication patterns
  • 📝 Draw a table for easy mapping of letters to codes
  • ⏱ Practice to increase speed

Common Mistakes to Avoid

  • Ignoring the pattern and guessing
  • Confusing letter and number shifts
  • Forgetting case sensitivity
  • Skipping step-by-step verification

Example Question

Problem: If APPLE → BQQMF, then MANGO → ?
Hint: Each letter is shifted +1 in alphabetical order.

Top 25 Coding-Decoding Questions

Q1. If CAT → DBU, then DOG → ?

Q2. In a certain code, APPLE → 12345, BANANA → 678787. What is the code for MANGO?

Q3. If TREE → UFSD, then LEAF → ?

Q4. In a code language, CAT → 312, DOG → 645. Find the code for BAT.

Q5. If in a code, A → 1, B → 2, … Z → 26, then what is the code for BOOK?

Q6. If PAPER → QBQFS, then PENCIL → ?

Q7. In a certain code, BLUE → RED, GREEN → BLUE, YELLOW → GREEN. What is the code for YELLOW?

Q8. If in a code, + → ×, − → +, × → −, then 6 + 2 − 3 × 2 = ?

Q9. If JUMP → KVNQ, then PLAY → ?

Q10. In a code language, DOG → 415, CAT → 312, find code for RAT.

Q11. If APPLE → AQQMF, then BANANA → ?

Q12. In a code language, letters are shifted +2. If BOOK → ?

Q13. If 1 → A, 2 → B, …, 26 → Z, then the word for 20 18 5 5 is?

Q14. If in a code, SUN → VXP, then MOON → ?

Q15. If COW → 324, PIG → 791, find the code for CAT.

Q16. In a code, LEFT → TGJUY, then RIGHT → ?

Q17. If CAT → BZV, DOG → CNF, find FISH → ?

Q18. If letters are coded as: A → Z, B → Y, C → X, find code for HELLO.

Q19. In a code language, FRIEND → GSKFOE, then LOVER → ?

Q20. If TABLE → UBCMF, then CHAIR → ?

Q21. In a code, ALPHA → BMQIB, then OMEGA → ?

Q22. If SCHOOL → TDPIPM, then TEACHER → ?

Q23. If WORD → 2314, then DRAW → ?

Q24. In a code, letters are reversed (A → Z, B → Y, etc.). Find code for MATH.

Q25. If in a code, each letter is replaced by the next alternate letter in the alphabet, then FUN → ?

Answer

Coding-Decoding – Answers

Q1. EPH
Q2. 1317147
Q3. MGBH
Q4. 214
Q5. 215116
Q6. QFOEJMM
Q7. GREEN
Q8. 6 × 2 + 3 − 2 = 13
Q9. QMBZ
Q10. 418
Q11. CBPBOB
Q12. DQQM
Q13. TREE
Q14. ORRQ
Q15. 324
Q16. SHJGU
Q17. GJTI
Q18. SVOOL
Q19. MPEXFS
Q20. UCBJS
Q21. PNFHB
Q22. UFBDIFS
Q23. 4132
Q24. NZSGS
Q25. GXO