Coding Decoding
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Cheat Sheets
Study MaterialCoding Decoding – Cheat Sheet
Coding Decoding is one of the most important and frequently tested topics in Logical Reasoning, appearing regularly in SSC, Banking, Railway, UPSC, Defence, Insurance, CAT, and other competitive examinations.
This cheat sheet helps candidates solve coding decoding problems involving letter coding, number coding, symbol coding, mixed coding, shifting patterns, positional values, and various coding rules. It covers shortcut techniques for quick and accurate problem-solving.
About This Cheat Sheet
Complete guide to Coding Decoding for competitive exams:
Letter Coding
- Forward/Backward Positions
- Reverse Alphabet
- Skip Patterns
- Alphabetical Positions
Number Coding
- Positional Numbers
- Sum of Positions
- Product of Positions
- Digit Sum Operations
Symbol Coding
- Symbols for Letters
- Symbols for Numbers
- Mixed Symbol Patterns
- Decoding Symbols
Mixed Coding
- Letters + Numbers
- Letters + Symbols
- Numbers + Symbols
- Combination Codes
Shift Coding
- Caesar Cipher
- Fixed Shift (+1, +2, etc.)
- Variable Shift
- Alternate Shift
Pattern Coding
- Letter-to-Letter Mapping
- Number-to-Letter Mapping
- Analogy Coding
- Pattern Recognition
Decoding
- Finding Original Word
- Reverse Engineering
- Rule Identification
- Application of Rules
Shortcut Techniques
- Quick Pattern Recognition
- Elimination Method
- Position Value Tricks
- Exam-Oriented Tips
Topics Covered
This cheat sheet covers all important Coding Decoding topics for quick revision:
| Topic | Description | Key Rule / Formula |
|---|---|---|
| Forward Positional Coding | A=1, B=2, C=3, ... Z=26 | MAP → 13,1,16 |
| Reverse Positional Coding | A=26, B=25, C=24, ... Z=1 | MAP → 14,26,11 |
| Fixed Shift Coding | Shifting each letter by fixed positions | CAT → FDU (+3) |
| Variable Shift Coding | Different shift for each letter | CAT → DBV (+1,+2,+3) |
| Reverse Alphabet Coding | A↔Z, B↔Y, C↔X, ... | CAT → XZG |
| Sum of Positions | Adding positional values of letters | CAT → 3+1+20=24 |
| Product of Positions | Multiplying positional values | CAT → 3×1×20=60 |
| Digit Sum Coding | Sum of digits of positional values | CAT → 3+1+2+0=6 |
| Symbol Coding | Symbols representing letters/numbers | @ # ! → CAT |
| Mixed Coding | Combination of letters, numbers, symbols | C1A2T3 → D4B5U6 |
| Decoding | Finding original word from code | FDU → CAT (-3) |
Key Rules & Reference Tables
Alphabet Positions
| Letter | Pos | Rev | Letter | Pos | Rev |
| A | 1 | 26 | N | 14 | 13 |
| B | 2 | 25 | O | 15 | 12 |
| C | 3 | 24 | P | 16 | 11 |
| D | 4 | 23 | Q | 17 | 10 |
| E | 5 | 22 | R | 18 | 9 |
| F | 6 | 21 | S | 19 | 8 |
| G | 7 | 20 | T | 20 | 7 |
| H | 8 | 19 | U | 21 | 6 |
| I | 9 | 18 | V | 22 | 5 |
| J | 10 | 17 | W | 23 | 4 |
| K | 11 | 16 | X | 24 | 3 |
| L | 12 | 15 | Y | 25 | 2 |
| M | 13 | 14 | Z | 26 | 1 |
Coding Types
| Type | Example |
| Direct Coding | A→D, B→E, C→F |
| Shift Coding | CAT → FDU (+3) |
| Reverse Coding | CAT → XZG |
| Pattern Coding | CAT → DBU (+1,+2,+1) |
| Positional | CAT → 3,1,20 |
| Reverse Positional | CAT → 24,26,7 |
| Sum Coding | CAT → 24 |
| Product Coding | CAT → 60 |
Common Shifts
| Shift | Example |
| +1 | CAT → DBU |
| -1 | CAT → BZS |
| +2 | CAT → ECV |
| -2 | CAT → AYR |
| +3 | CAT → FDU |
| -3 | CAT → ZXQ |
| +1,-1 | CAT → DBS |
| +1,+2,+3 | CAT → DBV |
Strategies
| Strategy | Action |
| Identify Pattern | Look for repeating pattern |
| Find Shift | Determine fixed shift between letters |
| Check Position | Use A=1, B=2, etc. |
| Check Reverse | Use A=26, B=25, etc. |
| Sum/Product | Add or multiply positions |
| Elimination | Eliminate incorrect options |
Why This Cheat Sheet is Important
Master Multiple Coding Types
Learn letter coding, number coding, symbol coding, and mixed coding with confidence.
Identify Patterns Quickly
Recognize coding patterns and apply the correct rule in seconds.
Apply Positional Values
Use A=1, B=2 and reverse positions for fast decoding.
High Exam Weightage
Coding Decoding questions appear in almost every competitive exam.
Competitive Exams Covered
- SSC CGL
- SSC CHSL
- SSC MTS
- Bank PO & Clerk
- IBPS Exams
- Railway Recruitment Exams
- UPSC CSAT
- Defence Exams
- Insurance Exams
- CAT
- State Government Exams
Quick Exam-Oriented Examples
Question 1:
If CAT is coded as FDU, then how is DOG coded?
Step 1: CAT → FDU: C→F (+3), A→D (+3), T→U (+1)
Step 2: Wait, T→U is +1, not +3. Let's check again.
Step 3: C=3, F=6 (+3); A=1, D=4 (+3); T=20, U=21 (+1)
Step 4: Pattern: +3, +3, +1. Let's apply to DOG:
Step 5: D=4 → G=7 (+3); O=15 → R=18 (+3); G=7 → H=8 (+1)
Answer: GRH
Question 2:
If CODE is coded as EPFG, then what is BOOK coded as?
Step 1: CODE → EPFG: C→E (+2), O→P (+1), D→F (+2), E→G (+2)
Step 2: Pattern: +2, +1, +2, +2. Apply to BOOK:
Step 3: B→D (+2); O→P (+1); O→Q (+2); K→M (+2)
Answer: DPQM
Question 3:
If CAT is coded as XZG, then how is DOG coded? (Use reverse alphabet)
Step 1: Reverse alphabet: A↔Z, B↔Y, C↔X, D↔W, etc.
Step 2: C→X, A→Z, T→G ✓
Step 3: Apply to DOG: D→W, O→L, G→T
Answer: WLT
Question 4:
If CAT is coded as 3, 1, 20, then how is DOG coded?
Step 1: CAT → C=3, A=1, T=20
Step 2: Apply positional values to DOG:
Step 3: D=4, O=15, G=7
Answer: 4, 15, 7
Question 5:
If CAT is coded as 24, then how is DOG coded? (Sum of positions)
Step 1: CAT: C=3, A=1, T=20 → 3+1+20 = 24
Step 2: DOG: D=4, O=15, G=7 → 4+15+7 = 26
Answer: 26
Question 6:
If CAT is coded as 60, then how is DOG coded? (Product of positions)
Step 1: CAT: C=3, A=1, T=20 → 3×1×20 = 60
Step 2: DOG: D=4, O=15, G=7 → 4×15×7 = 420
Answer: 420
Question 7:
If @ represents A, # represents B, $ represents C, then what is @#$?
Step 1: @ = A, # = B, $ = C
Step 2: @#$ = A B C
Answer: ABC
Question 8:
If C1A2T3 is coded as D4B5U6, then how is D4O5G7 coded?
Step 1: C→D (+1), 1→4 (+3), A→B (+1), 2→5 (+3), T→U (+1), 3→6 (+3)
Step 2: Pattern: Letter +1, Number +3
Step 3: Apply to D4O5G7: D→E, 4→7, O→P, 5→8, G→H, 7→10
Answer: E7P8H10
Question 9:
If FDU is coded as CAT, then what is JQJ coded as? (Same rule)
Step 1: FDU → CAT: F→C (-3), D→A (-3), U→T (-1)
Step 2: Pattern: -3, -3, -1
Step 3: Apply to JQJ: J→G (-3), Q→N (-3), J→I (-1)
Answer: GNI
Question 10:
If CAT is coded as DBV, then how is DOG coded?
Step 1: CAT → DBV: C→D (+1), A→B (+2), T→V (+2)
Step 2: Pattern: +1, +2, +2. Apply to DOG:
Step 3: D→E (+1); O→Q (+2); G→I (+2)
Answer: EQI
Question 11:
If CAT is coded as 6, then how is DOG coded? (Digit sum of positions)
Step 1: CAT: C=3, A=1, T=20 → 3+1+20=24 → 2+4=6
Step 2: DOG: D=4, O=15, G=7 → 4+15+7=26 → 2+6=8
Answer: 8
Final Takeaway
Coding Decoding questions test your ability to identify patterns and apply rules consistently. The key is to recognize the type of coding being used — letter shift, positional values, reverse alphabet, sum/product, or mixed coding — and apply the same rule to the new word.
Regular practice of various coding patterns and decoding techniques will significantly improve your speed and accuracy. This cheat sheet serves as a complete revision resource for mastering Coding Decoding questions in competitive examinations.
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Everything You Need for Coding Decoding Revision
Explore letter coding, number coding, symbol coding, mixed coding, shift patterns, positional values, sum/product coding, decoding techniques, and shortcut methods in one place for quick and effective revision.
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