Reasoning – Coding-Decoding
What is Coding-Decoding?
This topic involves converting words or letters into a coded form and decoding them using logical rules. It's used to test your ability to spot letter/number patterns and substitutions.
Types of Coding
1. Letter Coding: Each letter is replaced based on its position or rule (e.g., shift by +1).
2. Number Coding: Words are represented by numbers based on position or sum of values.
3. Substitution Coding: One word or character is replaced by another as per instructions.
4. Symbol Coding: Assigning codes using symbols for letters/numbers.
Example Questions
- If CAT is coded as DBU, how is DOG coded?
Answer: EPH (Each letter +1)
- If TEA = 25, how is BAT coded?
Answer: 23 (B=2, A=1, T=20 → 2+1+20=23)
- In a code, BLUE is GREEN, GREEN is RED, RED is YELLOW. What is the color of blood?
Answer: YELLOW (Blood is RED, but RED=YELLOW in code)
Exam Tips
- Convert letters to number positions (A=1 to Z=26).
- Check for consistent rules like +1, −1, reverse, position swap, etc.
- Practice with both direct and reverse coding.
- Analyze code patterns in full word, not just initials.
Common Mistakes
- Assuming random codes without validating the logic.
- Forgetting to apply the same rule uniformly to all letters.
- Ignoring position-based shifts or mirror logic (e.g., A↔Z, B↔Y).
Quick Revision Checklist
- Memorize letter positions and common shifts.
- Practice sum-based number codings.
- Solve 20+ problems involving both encoding and decoding.
- Apply reverse logic if code looks backwards.
Summary: Coding-Decoding tests your ability to detect patterns in transformations. Mastery requires familiarity with letter positions, shift logic, and substitution techniques.