Coding Decoding Reasoning Questions: Complete Guide with Tricks, Examples And Quiz

Coding Decoding Introduction

Coding Decoding is one of the most popular and scoring topics in the reasoning sections of competitive exams like SSC, IBPS, Railway, and other government job tests. In this type of reasoning, words, numbers, or letters are coded using a particular pattern or rule, and candidates are asked to decode the message or apply the same rule to new words. It tests your logical thinking, attention to detail, and ability to recognize hidden patterns within a limited time.

Since coding decoding reasoning questions frequently appear in exams and can be solved quickly with the right approach, mastering this topic can give you an edge in the reasoning section. In this guide, we’ll cover everything you need from basic concepts to different types of coding decoding questions, along with shortcut tricks, solved examples, and a practice quiz.

Coding decoding reasoning questions Quiz and Download Link

Before we dive into Coding and Decoding Reasoning, let’s test your skills with a quick quiz! This fun quiz will help you check how well you understand Coding and Decoding concepts. Once you finish the quiz, you can also download a complete set of Coding-Decoding Reasoning Questions for extra practice.

Want to challenge yourself with Coding-Decoding Reasoning quizzes? Click the links below to play and sharpen your reasoning skills!

👉 Coding Decoding Reasoning Questions Quiz -1

👉 Coding Decoding Reasoning Questions Quiz – 2

What is Coding-Decoding in Reasoning?

Coding-Decoding is a reasoning topic where words, numbers, or letters are written in a secret pattern called a ‘code’, and you have to decode it to find the original message or apply the same rule to new words. In simple terms, coding means converting a message into a secret form, and decoding means converting it back to its original form.

For example, if CAT is coded as DBU, it means each letter is replaced by the next letter in the English alphabet (C→D, A→B, T→U). In exams, you’ll be asked to find such hidden patterns and apply them to other words. It tests your logical ability to recognize patterns and relationships between letters and numbers.

Importance of Coding-Decoding in Competitive Exams

Coding-Decoding is one of the most frequently asked topics in the reasoning section of various competitive exams like SSC CGL, CHSL, IBPS PO, Clerk, Railway, and State-level exams. In most of these exams, you can expect 2 to 5 questions from Coding-Decoding, sometimes even more in reasoning heavy papers.

The best part is that these questions are easy to score and less time consuming if you understand the basic tricks and patterns. Many students lose marks in reasoning due to lengthy puzzles and seating arrangements, but Coding-Decoding offers a quick way to secure marks in less than a minute per question.

That’s why every serious aspirant should master this topic. It not only boosts your reasoning score but also improves your overall exam performance by saving valuable time.

Position of Letters in English Alphabet

To solve Coding Decoding reasoning questions easily, it’s very important to know the position of letters in the English alphabet. Most coding-decoding patterns are based on shifting positions of letters either forward, backward, or in a specific arrangement. Let’s understand this step by step.

Forward and Backward Positions of Letters

In reasoning, every letter in the English alphabet is given a numerical position.

• Forward Order means assigning numbers from A = 1, B = 2, C = 3… Z = 26.

• For example: A = 1, B = 2, C = 3, ……..  Z = 26

• Backward Order means counting positions in reverse, i.e. Z = 1, Y = 2, X = 3… A = 26.

• For example: A = 26, B = 25, C = 24, ……… Z = 1

Example:

If someone asks, what is the backward position of letter D?
Forward position of D = 4
Backward position of D= 27 – 4 = 23

Circular Arrangement Explanation

In some reasoning questions, alphabets are arranged in a circular order. In this case:

• After Z, it continues again from A in a circular manner.

• Similarly, before A, it moves back to Z.

For example:

• 1 letter ahead of Z is A

• 1 letter behind A is Z

This concept is used in problems where letters are shifted multiple positions ahead or behind in the alphabet.

Example:

If someone asks, what will be 3 letters ahead of Y in a circular arrangement?
Counting forward: Y → Z → A → B
Answer: B

How Positions Are Used in Coding-Decoding Problems

Now, you understand forward, backward, and circular arrangements, let’s see how these are applied in coding-decoding reasoning questions.

1). Position Shifting

In this method, each letter in a word is replaced by another letter obtained by moving it a certain number of positions forward or backward.

Example:

If each letter in the word CAT is moved 1 position forward:
C → D
A → B
T → U

Code: DBU

Similarly, if you move each letter 2 positions backward:
C → A
A → Y
T → R

Code: AYR

2). Replacing Letters with Number Positions

Sometimes, letters are replaced directly by their numeric positions in the alphabet.

Example:

‘DOG’ can be coded as:
D = 4
O = 15
G = 7

Code: 4-15-7

Or by using backward positions:
D = 27-4 = 23
O = 27-15 = 12
G = 27-7 = 20

Code: 23-12-20

3). Alternating Shifts (Forward & Backward)

A common pattern in coding-decoding problems is shifting alternate letters forward and backward.

Example:

If GOODNESS is coded as HNPCODTR

• G → H (1 forward)

• O → N (1 backward)

• O → P (1 forward)

• D → C (1 backward)

And so on…

4). Circular Letter Shifting

When shifting letters by positions beyond Z or before A, the circular arrangement is applied.

Example:

If you move 1 position forward from Z
Z → A

If you move 2 positions backward from A
A → Z (1 backward) → Y (2 backward)

Why coding-decoding is Important?

Almost 80% of coding-decoding problems rely on your ability to quickly identify the position of a letter in the English alphabet and shift it as per the given logic. Without memorizing these positions and understanding forward, backward, and circular movements, you’ll find it difficult to solve such questions quickly in exams like SSC, IBPS, or Railway.

Remember the shortcut formulas of coding-decoding

Types of Coding-Decoding Reasoning Questions

Type 1: Letter/Number Coding

In Letter/Number Coding, the letters of a word are replaced by other letters, numbers, or symbols following a specific pattern, rule, or logic to create a ‘code’. Your task is to identify this pattern and either decode the message or apply the same rule to another word. This is one of the most frequently asked coding-decoding question types in exams

The pattern could be based on:

• Changing positions of letters

• Replacing letters with numbers (their position values)

• Moving letters forward or backward in the alphabet

• A combination of these methods

Example 1:

In a certain code language,
‘GIVE’ is written as ‘VIEG’. How will ‘DISK’ be written in that code?

Options:
a) SIDK
b) KISD
c) KDSI
d) SIKD

Solution: Observe the pattern:

• The first letter moves to the last position

• The remaining letters shift one place to the left

GIVE → VIEG

• G → last

• I → 1st

• V → 2nd

• E → 3rd

Now apply the same pattern to DISK:

• D → last
• I → 1st
• S → 2nd
• K → 3rd

So, the code is: SIKD

Correct Answer: d) SIKD

Example 2:

If ‘WORK’ is coded as ‘4-12-9-16’, how will you code ‘WOMAN’?

Options:

a) 4-12-14-26-13
b) 4-26-14-13-12
c) 23-12-26-14-13
d) 23-15-13-1-14

Solution

Check the logic in WORK → 4-12-9-16
Given in the PDF explanation – each letter is coded as (27 – position of letter)

W = 23 → 27-23 = 4
O = 15 → 27-15 = 12
R = 18 → 27-18 = 9
K = 11 → 27-11 = 16

Now, apply the same to WOMAN:
W = 23 → 4
O = 15 → 12
M = 13 → 14
A = 1 → 26
N = 14 → 13

Code: 4-12-14-26-13

Correct Answer: a) 4-12-14-26-13

Type 2: Direct Coding

In Direct Coding, a word or sentence is coded by directly substituting each letter with another letter, number, or symbol according to a fixed rule.

The important point is that the sequence of the letters remains the same in both the word and its code only the characters are replaced based on a predefined code table or pattern.

Example:

If A = #, B = @, C = %, D = 5
Then, the word BAD would be coded as @#5

Example:

In a certain code language,
‘GONE’ is written as 5 % 2 #, and
‘MEDAL’ is written as 4 # 3 $ @.

How will GOLD be written in that code?

Options:
a) 5 @ % 3
b) 5 % @ 3
c) 5 # @ 3
d) 5 % # 3

Solution

From the given codes:
G = 5
O = %
N = 2
E = #
M = 4
D = 3
A = $
L = @

Now, code GOLD letter by letter:
G → 5
O → %
L → @
D → 3

So, the code is 5 % @ 3

Correct Answer: b) 5 % @ 3

Type 3: Conditional Coding

In Conditional Coding, a set of letters or numbers is given along with their corresponding codes. Alongside this, specific conditions are provided that affect how you encode or decode a particular word or group of letters.

Your job is to:

• Apply the given code for each letter

• Check the conditions carefully

• Modify the code for certain positions (like first or last letter) according to those conditions

This type of coding reasoning tests your attention to detail and ability to follow multiple rules simultaneously.

Important Conditions (Common Examples)

Some frequently seen conditions in exams are:

• If both the first and last letters are vowels, replace both with ‘$’

• If both the first and last letters are consonants, replace both with ‘#’

• If the first letter is a vowel and the last is a consonant, replace both with ‘%’

• If a letter is repeated, replace it with a specific symbol

• If the total number of letters is even, reverse the code

Note: Always read all conditions carefully – sometimes, more than one condition can apply, and priority will be given based on the question.

Example 1:

Directions:

Following letters are coded as:
P = 5, N = 3, A = 9, J = 1, I = 4, R = 6, E = 2, B = 7, U = 0, K = 8

Conditions:

• If both the first and last letters are vowels, replace both with ‘$’

• If both the first and last letters are consonants, replace both with ‘#’

Question:

What is the code for KUNAJB?

Options:
a) 803917
b) $0391$
c) #0391#
d) #0391$

Solution:

Letters: K U N A J B
Codes: 8 0 3 9 1 7

Now check the condition:

• K (first letter) = consonant

• B (last letter) = consonant

As per condition, both should be replaced with ‘#’

Code becomes: #0391#

Correct Answer: c) #0391#

Type 4: Substitution Coding

In Substitution Coding, names of objects, animals, days, numbers, or things are replaced by other unrelated names or words. In the question, specific substitution rules are given, and you are asked to answer based on those new assigned names – not their actual meaning.

It’s like playing a logic puzzle where you temporarily accept the new names and answer accordingly.

Important Point: Don’t get confused by the real meaning of words. Always answer based on the substitution rules provided in the question.

Example:

If
dog is called “cat”,
cat is called “lion”,
lion is called “rat”,

then which of these lives in a forest?

Options:
a) Rat
b) Lion
c) Dog
d) Cat

Solution

We know a lion lives in a forest.
But according to the question:
Lion is called rat.

So, the correct answer is Rat

Correct Answer: a) Rat

Type 5: Mixed Coding

In Mixed Coding, a few messages or sentences are given in a coded form using symbols, letters, or numbers. Here, the code words get mixed across multiple sentences – and by comparing the common words in the sentences, you have to figure out the meaning of each code.

It’s a logical decoding technique where you carefully match common words across different coded messages and identify their corresponding code values through elimination and comparison.

Example

In a certain code language:

• ‘134’ means ‘good and tasty’

• ‘478’ means ‘see good pictures’

• ‘729’ means ‘pictures are faint’

Question:

Which number represents ‘see’?

Solution:

Now, compare the sentences:

• ‘134’ = ‘good and tasty’

• ‘478’ = ‘see good pictures’

👉 Common word: ‘good’
👉 Common code: ‘4’

So,
‘4’ = ‘good’

Now, in ‘478’, the remaining codes are 7 and 8
And remaining words are ‘see’ and ‘pictures’

Now, check with ‘729’ = ‘pictures are faint’
👉 ‘pictures’ appears in both ‘478’ and ‘729’
👉 Code ‘7’ appears in both

So,
‘7’ = ‘pictures’

Now, in ‘478’ only one code remains: 8
And one word remains: ‘see’

So,
‘8’ = ‘see’

Correct Answer: 8

Type 6: Fictitious Language Coding

In Fictitious Language Coding, sentences or phrases are written in a made – up or imaginary language using invented words or letter groups. Your task is to decode the meaning of certain words based on the given sentences and their coded forms by comparing common words and their codes – similar to mixed coding, but usually involving entire sentences with unfamiliar words.

Key Approach:

• Compare sentences with common words

• Identify the code for those words

• Use elimination to decode other unknown words

Example

In a certain code language:

• ‘pik rak tok’ means ‘sky is blue’

• ‘mik tok lak’ means ‘blue and green’

• ‘rik sak pik’ means ‘sky is clear’

Question:
What is the code for ‘blue’?

Solution:

Now, compare the sentences:

• ‘pik rak tok’ = ‘sky is blue’

• ‘mik tok lak’ = ‘blue and green’

👉 Common word: ‘blue’
👉 Common code word: ‘tok’

So,
‘tok’ = ‘blue’

✅ Correct Answer: ‘tok’

FAQs about Coding-Decoding Reasoning

1. What is Coding-Decoding in Reasoning?

Answer: Coding – Decoding is a type of reasoning where words, numbers, or letters are converted into a particular code using a pattern, and candidates need to either decode the message or apply the same logic to new words. It tests logical thinking, pattern recognition, and decision-making speed.

2. Why is Coding-Decoding important for competitive exams?

Answer: Coding-Decoding questions are asked in almost every competitive exam like SSC, IBPS, Railway, and Defence exams. These questions are scoring, quick to solve, and can be attempted within seconds if you know the tricks, helping improve your overall reasoning score.

3. How can I improve my speed in Coding-Decoding Reasoning?

Answer: To improve speed, practice identifying common patterns like letter shifting, reverse order, position values, and substitution rules. Learn and memorize shortcut tricks like the EJOTY rule and practice daily with mock tests and quizzes to boost speed and accuracy.

4. What are the common types of Coding-Decoding questions?

Answer:

The most common types include:

• Letter/Number Coding

• Direct Coding

• Conditional Coding

• Substitution Coding

• Mixed Coding

• Fictitious Language Coding

Each type follows a different logic or pattern that you need to recognize quickly in exams.

Conclusion

Coding-Decoding is one of the most important and high-scoring topics in the reasoning section of competitive exams like SSC, IBPS, Railway, and State-level tests. The best part is that with a little regular practice, anyone can master this topic and solve these questions within seconds during exams.

Since most Coding-Decoding problems are based on simple patterns like letter shifting, number positions, substitution, and symbol replacement, learning a few smart shortcut tricks can make your preparation much easier and faster.

To stay sharp and improve your accuracy, it’s important to practice Coding-Decoding reasoning questions daily. Try different types of problems, time yourself, and gradually increase your speed.

Also, don’t forget to download the free practice PDF we’ve shared in this guide to test your skills and track your progress. Happy learning and best of luck for your exams!