SSC CGL Preparation – Day 6

Table of Contents

Reasoning – Coding-Decoding (Basic to Moderate Level)


πŸ” What is Coding-Decoding?

In coding-decoding, a word or a number is transformed into a secret code by following a certain rule or logic. The objective is to identify the logic used and apply it to find the answer.


🎯 Importance in SSC CGL

  • 2–3 questions are usually asked in Tier 1
  • Frequently asked and easy to score
  • Based on pattern recognition and vocabulary/logical analysis

🧩 Types of Coding-Decoding Questions


1. Letter Coding

A word is written in code using specific letter substitutions.

Example:
If COLD is coded as DPME, what is the code for WARM?

Solution:
Compare each letter:
C β†’ D (+1), O β†’ P (+1), L β†’ M (+1), D β†’ E (+1)
So, W β†’ X, A β†’ B, R β†’ S, M β†’ N
Answer: XBSN


2. Number Coding

Words are coded using numbers based on alphabetical positions.

Example:
If BAD is coded as 214, what is the code for ACE?

Solution:
A = 1, C = 3, E = 5
Answer = 135


3. Substitution Coding

Words are replaced with unrelated words. It’s vocabulary-based.

Example:
If β€œPen” is called β€œBook”, β€œBook” is called β€œPencil”, β€œPencil” is called β€œEraser”, then what do we write with?

Answer: β€œPencil” is used to write, and it’s called Eraser.


4. Mixed Letter Coding

Codes for 2–3 statements are given. We must deduce the code for a word by comparing statements.

Example:

  1. β€œRavi is good” β†’ ka la ma
  2. β€œHe is bad” β†’ la na da

What is the code for is?

Solution:
Common word = β€œis”, common code = la
Answer: la


5. Matrix Coding

A matrix is given with letters arranged in rows and columns. A letter is coded by referring to its position.

Example:

012
0ABC
1DEF
2GHI

Code for E = 11


6. Symbol Coding / Conditional Coding

Questions involve interpreting symbolic logic and conditional assignments.

Example:
If β€˜+’ means β€˜Γ—β€™, β€˜Γ—β€™ means β€˜β€“β€™, β€˜β€“β€™ means β€˜Γ·β€™, β€˜Γ·β€™ means β€˜+’, then
20 – 5 Γ— 2 = ?

Replace:
20 Γ· 5 – 2 = 4 – 2 = 2


7. Decoding Based on Alphabetical Positions

Sometimes questions involve direct manipulation of alphabetic positions (A = 1, B = 2 … Z = 26)

Example:
If HAND is coded as 85144, find the code for FIND.

F = 6, I = 9, N = 14, D = 4
Answer: 69144


πŸ“˜ Tips & Tricks

  1. Memorize Alphabet Positions:
    A=1, B=2, …, Z=26
    (Reverse: Z=1, Y=2, … A=26 – for reverse coding)
  2. Check Pattern of Shifts:
    +1, –2, alternate letters, etc.
  3. Use Elimination in MCQs
    Narrow down options based on even one letter decoded.
  4. Compare Similar Words
    In sentence coding, compare common words.

πŸ“ Common Alphabet Positions (for quick recall)

AEIMQUY
15913172125
BFJNRVZ
261014182226

πŸ§ͺ Practice this flow:

  1. Identify type of coding
  2. Map original & coded word
  3. Spot consistent logic or rule
  4. Apply the same rule to new word
  5. Eliminate options logically

Leave a Reply

Your email address will not be published. Required fields are marked *