Q47·CSAT · Prelims 2026
Logic — Alphabetic Shift Ciphering
ReasoningCoding-Decoding — Letter ShiftCoding-Decoding● Easy
Question
If ZERO is encoded as ADSN, then how do you encode STOP? [cite: 4460, 4461, 4500]
Options
a
SPOT
bAnswer
TSPO
c
TSOP
d
POST
Explanation
Let us analyze the cryptographic character shifts between the source word ZERO and its encoded output ADSN:
Z +1 A (wraps around the alphabet index)
E -1 D
R +1 S
O -1 N
This reveals a repeating alternating offset rule of [+1, -1, +1, -1]. Let us apply this exact pattern to the target word STOP:
S +1 T
T -1 S
O +1 P
P -1 O
Combining these letters yields the output string TSPO.
Alternating shift patterns are solved efficiently by finding the exact step changes for the first two characters and applying them uniformly to the target word.
Answer: (b).
Question details
Year
2026
Paper
CSAT
Question
Q47
Section
Logical Reasoning
Sub-topic
Coding-Decoding — Letter Shift
Type
Coding-Decoding
Difficulty
Easy
Source hint
Cryptographic ciphers — fixed progressive character offsets
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