🧠 Coding and Decoding – Logical Reasoning

📌 What is Coding and Decoding?

Coding is a method of transmitting a message in such a way that only the intended person can understand it.
Decoding is the process of interpreting or converting the coded message back into its original form.

In reasoning questions, coding-decoding tests your ability to:

• • Recognize letter/number patterns
• • Understand symbol-language mapping
• • Decode logic used in word or number transformations

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🎯 Why It’s Important

• • Appears frequently in logical reasoning sections of competitive exams
• • Tests mental sharpness, logic, and observation skills
• • Enhances analytical thinking and pattern recognition

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📚 Types of Coding-Decoding Questions

1. Letter Coding

- One word is coded as another using a pattern of letters.

- Example: If TABLE is coded as UBCMF, how is CHAIR coded?

- Solution: T→U (+1), A→B (+1), B→C (+1), L→M (+1), E→F (+1) → CHAIR → DIBJS ✅

2. Number Coding

- Words are coded into numbers based on letter positions or patterns.

- Example: If DOG is coded as 4157, how is CAT coded?

- Solution: D=4, O=15, G=7 → C=3, A=1, T=20 → Answer: 31120

3. Substitution Coding

- Words are replaced with other words or symbols, like a secret language.

- Example: If 'blue' is called 'green', 'green' is called 'red', what is the color of grass?

- Answer: Grass is normally green → 'green' is coded as 'red' → Answer = red

4. Letter Position Coding (Alphabetical Series Logic)

- Each letter's position is used in logic (A = 1, B = 2, ..., Z = 26).

- Example: If ACE = 135, what is BDF?

- Solution: B=2, D=4, F=6 → Answer: 246

5. Mixed Coding (Coding by Sentences)

- Full sentences are coded using random words or symbols.

- Example:
"Ram eats mango" → "mi lo ta"
"mango is sweet" → "ta ki su"
What is the code for “mango”?
✅ Common word = “mango” → common code = ta

6. Matrix Coding

- A matrix of letters/numbers is used for finding codes.

- Example: Matrix with rows and columns, you are told to find the letter at Row 2, Column 3, etc.
(Used rarely, more common in advanced reasoning.)

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✅ Common Tricks and Tips

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🧩 Sample Practice Questions

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💡 Advanced Coding Patterns

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🏁 Conclusion

Coding and decoding improves:

• • Vocabulary
• • Logic building
• • Observation skills
• • Pattern recognition

✅ It’s all about logic + practice.