SBI Clerk · Bite-size lessons

Coding-Decoding

About 6 min · Reasoning Ability · English

Time worked out from the lesson's 347 words at 150 words a minute, plus a minute for each question.

This topic tests your ability to identify hidden patterns in how letters, numbers, or symbols are transformed according to a specific rule. The examiner encodes a word using a particular logic, and you must crack that logic to decode new words or find the code for given words.

Key ideas

• Letter Shifting: Each letter moves forward or backward in the alphabet by a fixed number (e.g., A→C means +2 shift). The shift can be uniform or positional (1st letter +1, 2nd letter +2, etc.).
• Reverse Order Coding: The letters of the word are simply written in reverse order, sometimes combined with a shift.
• Opposite Letter Coding: Each letter is replaced by its opposite in the alphabet (A↔Z, B↔Y, C↔X). Remember: Letter + Opposite = 27.
• Position-Based Coding: Letters are replaced by their alphabetical position numbers (A=1, B=2... Z=26) or vice versa.
• Symbol/Number Substitution: Letters are replaced by symbols or numbers following a consistent pattern across all given examples.

Watch out for

• Assuming uniform shift without checking all letters → Always verify the pattern holds for every letter in the given example before applying.
• Forgetting cyclic nature of alphabet → When Z+3 is needed, count Z→A→B→C, answer is C, not stuck at Z.
• Confusing opposite letter calculation → Don't subtract from 26; the sum of positions equals 27. Opposite of C(3) is X(24) because 3+24=27.

Quick reference

• Opposite letters always sum to 27: A(1)+Z(26)=27
• EJOTY: E=5, J=10, O=15, T=20, Y=25 — your anchor points
• First check: Is it simply reversed? Then check opposite letters. Then check shifts.
• Positional shift pattern: 1st letter +1, 2nd letter +2, 3rd letter +3...
• Sentence coding: Find common word between two sentences = find common code

Check yourself: 3 questions

This lesson is cut from the topic's note, not rewritten. Fact-checked on 18 Oct 2026: an AI-assisted check of this note against cited sources; the errors it found were corrected that day. Some errors may remain. The questions are from Shishya's validated question bank.

Read the full noteFlashcards for this topic