Coding and Decoding: Complete Notes for CUET, CLAT, IPMAT
Introduction:
Coding and Decoding is a common topic in logical reasoning sections of exams like CUET, CLAT, and IPMAT. In these questions, a word or number is coded in a particular manner, and the same logic is applied to decode or code another word or number.
These questions test:
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Analytical thinking
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Pattern recognition
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Vocabulary (occasionally)
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Attention to detail
Types of Coding-Decoding
1. Letter Coding
In this type, alphabets are replaced with other alphabets.
Example:
If CAT is coded as DBU, what is the code for DOG?
Solution:
C → D (+1), A → B (+1), T → U (+1)
So, D → E, O → P, G → H → Answer: EPH
2. Number Coding
Words are coded in numbers or vice versa.
Example:
If BAD = 7 and ACE = 9, then what is the code for BED?
Solution:
B = 2, A = 1, D = 4 → 2+1+4 = 7
A = 1, C = 3, E = 5 → 1+3+5 = 9
BED = B(2) + E(5) + D(4) = 11
3. Substitution Coding
Here, certain words are substituted with arbitrary words.
Example:
If "blue" means "hot", "hot" means "cold", what is the color of fire?
Solution:
If fire is generally "hot", and "hot" means "cold", then fire is "cold".
4. Mixed Letter Coding
A sentence is coded in a jumbled way, often requiring decoding across multiple sentences.
5. Conditional Coding
Rules are given for encoding certain data, and the question involves applying these rules.
6. Binary Coding
Here, words or numbers are converted into binary formats or a binary-like logic is used.
Strategies to Solve
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Observe positions of letters in the alphabet (A=1 to Z=26).
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Check for sequences – are letters/numbers incremented or decremented?
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Look for patterns across multiple examples.
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For substitution, build a mapping dictionary.
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Practice common codes, such as:
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A=1, B=2…Z=26
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Reverse order: A=26, B=25…Z=1
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Previous Year Questions and Solutions
🔶 CUET PYQ 2023
Q1. If in a code, DELHI is written as EDMIJ, how will MUMBAI be written?
Solution:
Observe changes:
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D → E (+1)
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E → D (–1)
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L → M (+1)
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H → I (+1)
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I → J (+1)
Rule is alternating +1 and –1:
Apply to M U M B A I
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M → N (+1)
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U → T (–1)
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M → N (+1)
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B → C (+1)
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A → B (+1)
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I → J (+1)
Answer: NTNCBJ
Q2. In a certain code, PENCIL is written as QFODJM. How will ERASER be written?
Solution:
P → Q, E → F, N → O, C → D, I → J, L → M → +1 pattern
Apply +1:
E → F
R → S
A → B
S → T
E → F
R → S
Answer: FSBTF
🔶 CLAT PYQ 2022
Q3. If TOGETHER is written as SUHDSGDS, how is SUCCESS written?
Solution:
Compare T → S, O → U, G → H, etc.
Pattern:
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T → S (–1)
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O → U (+6)
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G → H (+1)
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E → D (–1)
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T → S (–1)
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H → G (–1)
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E → D (–1)
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R → S (+1)
Difficult pattern. Check logic with alternate –1, +1, +6.
Now try coding SUCCESS:
S → R (–1)
U → V (+1)
C → B (–1)
C → D (+1)
E → D (–1)
S → T (+1)
S → R (–1)
Seems alternating –1, +1. Apply:
RVB DDT R
Answer: RVBDTTR
Q4. In a code language:
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‘Bank is open’ → ‘me re ka’
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‘Open the account’ → ‘ka de ji’
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‘Bank account closed’ → ‘me ji lo’
What is the code for ‘Bank’?
Solution:
Compare sentences:
‘Bank is open’ = me re ka
‘Bank account closed’ = me ji lo
Common word = "Bank" → Common code = me
🔶 CUET/CLAT/IPMAT PYQs with Detailed Solutions
Q1.
In a certain code, STOVE is written as FNBLK. How will VOTES be written in that code?
Solution:
Let’s write the positions:
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S (19) → F (6)
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T (20) → N (14)
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O (15) → B (2)
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V (22) → L (12)
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E (5) → K (11)
Pattern:
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S(19) – 13 = 6 → F
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T(20) – 6 = 14 → N
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O(15) – 13 = 2 → B
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V(22) – 10 = 12 → L
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E(5) + 6 = 11 → K
The pattern isn’t uniform — but the letter positions match by consistent changes.
Now decode VOTES:
V(22) – 13 = 9 → I
O(15) – 6 = 9 → I
T(20) – 13 = 7 → G
E(5) – 10 = –5 → Z (26 – 5 = 21)
S(19) + 6 = 25 → Y
Answer: IIGZY
Q2.
If COLD is coded as DPME, how is HEAT coded?
Solution:
C → D (+1)
O → P (+1)
L → M (+1)
D → E (+1)
Apply +1 to HEAT:
H → I
E → F
A → B
T → U
Answer: IFBU
Q3.
In a certain code, TEACH is written as VGCEJ. How is LEARN written?
Solution:
T → V (+2)
E → G (+2)
A → C (+2)
C → E (+2)
H → J (+2)
Pattern: +2 for each letter
LEARN:
L → N
E → G
A → C
R → T
N → P
Answer: NGCTP
Q4.
If in a certain code PAPER is written as QBQFS, how is PEN written?
Solution:
Each letter is +1:
P → Q
E → F
N → O
Answer: QFO
Q5.
If LION is coded as MJPO, then how is TIGER coded?
Solution:
L → M (+1)
I → J (+1)
O → P (+1)
N → O (+1)
Apply same for TIGER:
T → U
I → J
G → H
E → F
R → S
Answer: UJHFS
Q6.
In a code language, JUMP is written as KVOQ, how will MOVE be written?
Solution:
J → K (+1)
U → V (+1)
M → O (+2)
P → Q (+1)
Assuming +1 or +2 alternation.
M → N (+1)
O → P (+1)
V → W (+1)
E → F (+1)
Answer: NPWF
Q7.
In a certain code, TRUST is written as USVTU. How is FAITH written?
Solution:
T → U (+1)
R → S (+1)
U → V (+1)
S → T (+1)
T → U (+1)
Pattern: +1
F → G
A → B
I → J
T → U
H → I
Answer: GBJUI
Q8.
If MANGO is coded as OBPGQ, how will APPLE be written?
Solution:
M → O (+2)
A → B (+1)
N → P (+2)
G → G (0)
O → Q (+2)
Apply same:
A → B (+1)
P → R (+2)
P → P (0)
L → N (+2)
E → G (+2)
Answer: BRPNG
Q9.
In a certain language, FLOWER is written as GNQXFS. How is GARDEN written?
Solution:
F → G (+1)
L → N (+2)
O → Q (+2)
W → X (+1)
E → F (+1)
R → S (+1)
Pattern = +1 or +2 alternation
G → H
A → C
R → T
D → E
E → G
N → O
Answer: HCTEGO
Q10.
If DOOR is written as FQQT, how is GATE written?
Solution:
D → F (+2)
O → Q (+2)
O → Q (+2)
R → T (+2)
Same +2:
G → I
A → C
T → V
E → G
Answer: ICVG
Q11.
If KING is coded as LKOI, how will QUEEN be coded?
Solution:
K → L
I → K
N → O
G → I
Pattern: +1, +2
Q → R
U → W
E → F
E → F
N → O
Answer: RWFFO
Q12.
If SMART is written as UNCRA, how is HAPPY written?
Solution:
S → U (+2)
M → N (+1)
A → C (+2)
R → R (0)
T → A (–19, possibly reverse)
Doesn't follow perfect pattern.
Try H → J (+2)
A → B (+1)
P → R (+2)
P → P (0)
Y → B (wrap –23)
Answer: JBRPB
Q13.
If APPLE is 50, ORANGE is 60, then MANGO is?
Solution:
A=1, P=16, L=12, E=5 → 1+16+16+12+5 = 50
O=15, R=18, A=1, N=14, G=7, E=5 = 60
MANGO = M(13)+A(1)+N(14)+G(7)+O(15) = 50
Answer: 50
Q14.
In a certain code, TALL is UBMM. What is the code for SHORT?
Solution:
T → U (+1)
A → B (+1)
L → M (+1)
L → M (+1)
So apply +1:
S → T
H → I
O → P
R → S
T → U
Answer: TIPSU
Q15.
In a code:
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‘Come home soon’ = ‘la ma na’
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‘He comes today’ = ‘ta sa la’
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‘Home today nice’ = ‘ma sa pa’
What is the code for ‘today’?
Solution:
‘He comes today’ = ta sa la
‘Home today nice’ = ma sa pa
Common word: today → Common code: sa
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