This presentation focuses on one of the most important reasoning topics asked in almost every competitive exam: Coding and Decoding. It is designed to make the concepts simple and easy to understand for beginners as well as advanced learners. The slides explain different types of coding-decoding patterns, such as letter coding, number coding, symbol coding, mixed coding, and substitution coding. Each method is explained with clear examples, step-by-step solutions, and shortcut techniques to solve questions quickly. In addition, this presentation provides exam-oriented practice questions that will help learners apply the concepts directly in tests. These methods are especially useful for aspirants preparing for SSC, Banking, Railway, Insurance, IBPS, State PSCs, and other government or corporate aptitude tests. By the end of this presentation, learners will: Understand all common types of coding-decoding. Develop logical thinking and analytical ability. Apply shortcuts to solve questions within seconds. Practice exam-level problems with confidence. This resource is ideal for students, teachers, and competitive exam aspirants who want to strengthen their reasoning section and score high marks. The presentation is designed in a simple, engaging, and exam-oriented style to maximize learning and retention.

1. CODING
DECODING

2. 1. Letter Coding
🔷 Concept: Each letter is shifted by a rule (+1/–1 etc.)
🔸 PYQ 1: (SSC CHSL 2021)
Q. In a certain code language, FOG is written as GPH. How will MOP be written in that code?
A) NPQ
B) NOQ
C) NPP
D) MPQ
✅ Answer: A) NPQ
Explanation: F→G (+1), O→P, G→H ⇒ M→N, O→P, P→Q
🔸 PYQ 2: (SSC CGL 2019)
Q. If PEN is coded as QFO, how is DOG coded?
A) EPH
B) EOF
C) EPF
D) DPG
✅ Answer: A) EPH
Logic: +1 shift on each letter

3. 🔸 PYQ 2: (SSC CGL 2019)
Q. If PEN is coded as QFO, how is DOG coded?
A) EPH
B) EOF
C) EPF
D) DPG
✅ Answer: A) EPH
Logic: +1 shift on each letter
🔵 2. Number Coding
🔷 Concept: Letter positions are used (A=1 to Z=26)
🔸 PYQ 1: (SSC CHSL 2018)
Q. If BAG is written as 10, what is the code for TAP?
A) 30
B) 34
C) 37
D) 38
✅ Answer: C) 37
Logic: T=20, A=1, P=16 → Total = 37

4. 🔸 PYQ 2: (SSC CGL 2016)
Q. If CAT = 24, what will be the code for DOG?
A) 27
B) 26
C) 25
D) 28
✅ Answer: B) 26
Logic: D=4, O=15, G=7 → 4+15+7 = 26
3. Substitution Coding
🔸 PYQ 1: (SSC CHSL 2019)
Q. If ‘white’ is called ‘black’, ‘black’ is called ‘red’, and ‘red’ is
called ‘green’, then what is the color of blood?
A) Black
B) Green
C) Red
D) White
✅ Answer: B) Green
Logic: Blood = red → red is called green

5. 🔸 PYQ 2: (SSC MTS 2022)
Q. If ‘Train’ is called ‘Bus’, ‘Bus’ is called ‘Truck’, and ‘Truck’ is called ‘Van’, how do we travel on
rails?
A) Truck
B) Bus
C) Train
D) Van
✅ Answer: B) Bus
Logic: Train → called Bus

6. 4. Mixed Letter Coding
🔷 Concept: Compare coded sentences
🔸 PYQ 1: (SSC CGL Tier II 2017)
"Time is money" = la ro mi
"Money and life" = ro yo su
"Life is time" = mi su la
👉 What is the code for "money"?
A) ro
B) yo
C) mi
D) su
✅ Answer: A) ro

7. 🔸 PYQ 2: (SSC MTS 2021)
"Sun rises in east" = ka na ti la
"Moon rises in west" = ti na ro sa
👉 What is the code for "rises"?
A) ti
B) ka
C) ro
D) na
✅ Answer: D) na
Logic: Common in both = rises → na

8. 5. Mirror (Z-based) Coding
🔸 PYQ 1: (SSC CGL 2017)
Q. If in a certain code, letters are coded using their mirror positions (A↔Z), what is the code for DOG?
A) XLT
B) WKT
C) WLT
D) TUL
✅ Answer: C) WLT
D=4 → W(23), O=15 → L(12), G=7 → T(20)
🔸 PYQ 2: (SSC CHSL 2022)
Q. If RAIN is coded as IZRM, what is the code for SNOW?
A) HLMD
B) HMLD
C) HMLC
D) HMLB
✅ Answer: B) HMLD

9. 6. Pattern / Conditional Coding
🔸 PYQ 1: (SSC CGL 2020)
Q. If DELHI is coded as EFMIJ, then how will LUCKY be coded?
A) MVDLZ
B) MVELZ
C) LVCJX
D) MVCLZ
✅ Answer: A) MVDLZ
Logic: +1 to each letter
🔸 PYQ 2: (SSC CHSL 2022)
Q. If MANGO is written as NBOHP, how is GRAPE coded?
A) HSBQF
B) HSBPE
C) HSBPF
D) ISBPF
✅ Answer: A) HSBQF