Coding-Decoding Questions for SBI CLERK

Letter-Position Coding (A=1, Z=26)

The most classic type. Each letter is assigned a position value — A=1, B=2... Z=26. The code is formed by shifting letters forward or backward by a fixed number, or by reversing the alphabet (A=26, Z=1). SBI Clerk often pairs this with a small twist like +2 shift for consonants and -1 for vowels.

• A=1, B=2, C=3 ... Z=26 — memorize this as your base.
• Opposite letters: A-Z, B-Y, C-X, D-W, E-V ... use formula: Position + Opposite = 27.
• Forward shift by N: CAT with +2 gives ECV.
• Backward shift: CAT with -2 gives AYR.
• Always check if the shift is applied uniformly or alternately (odd/even positions treated differently).
• Reverse alphabet coding: A becomes Z, B becomes Y — same as opposite-letter coding.

Number Substitution Coding

Letters are replaced by numbers following a logic — could be position values, reverse position, or a custom table. SBI Clerk often gives 2-3 coded words and asks you to find the code for a new word. The trick is to compare common letters across given examples to isolate each letter's code.

• If BALL=2133 and CALL=3133, then B=2 and C=3 (rest are same).
• Always find letters that appear in multiple given codes — they anchor your decoding.
• Watch for reversed position coding: A=26, B=25 type.
• Sometimes numbers represent rank of the letter after rearranging the word alphabetically.
• Sum or product of position values may be given as the code for the whole word.

New Pattern: Sentence or Word-Shift Coding

SBI Clerk Mains and recent Prelims introduced a set-based format where 3-4 coded sentences are given and you deduce codes for individual words. This is like a puzzle. The method is: find sentences sharing the maximum number of words, isolate the unique word and its unique code. It is process of elimination.

• Given 3 sentences — compare any two, find common words, their codes must appear in both coded lines.
• The leftover code in one line = leftover word in that line.
• Word order in the coded sentence may not match — codes can be scrambled.
• Confirm your finding using the third sentence as a cross-check.
• This type rewards patience, not speed — spend 2-3 minutes systematically.

Symbol and Mixed Coding

Letters are replaced by symbols (#, @, %, $) or a mix of symbols and numbers. Logic can be: vowels get symbols, consonants get numbers, or it could be position-based. These appear occasionally in SBI Clerk Prelims as fillers.

• Identify vowels (A,E,I,O,U) and consonants separately — often coded differently.
• Check if symbols follow alphabetical sequence (@=1st symbol for A, #=2nd for B etc.).
• If given a full word in code, match letter frequency with symbol frequency.
• Do not waste more than 90 seconds on a symbol code you cannot crack — move on.

Conditional Coding (Table-Based)

A table maps digits to letters with conditions — for example, if the first letter is a vowel, use the code of the last letter instead, and vice versa. This type is common in SBI Clerk Mains. Read the conditions carefully before starting.

• Always read ALL conditions before coding even the first letter.
• Common conditions: vowel at start or end triggers a swap or special code.
• Draw a small table on your rough sheet — eliminates errors.
• Typically asked as a set of 5 questions sharing the same table — high return on time invested.
• If two conditions seem to conflict, re-read — usually one overrides the other explicitly.

• Assuming word order is preserved in sentence coding — it is often scrambled, so never match position, match frequency and elimination.
• Forgetting to check mod 26 when doing letter shifts — Z+1 wraps to A, not AA.
• Mixing up A=1 coding with reverse A=26 coding — always verify with the first given example before applying to the question.
• In conditional table coding, applying the condition to wrong letters — recheck whether the condition triggers on the original word or the code.
• Spending too long on a symbol code with no visible logic — in a 20-minute Reasoning section every second counts, so flag and move on.

• OPPOS = 27: Any letter plus its opposite equals 27. C(3) + X(24) = 27. Chant this while solving.
• CELI method for sentence coding: Compare, Eliminate, Lock, confirm with thIrd sentence.
• Vowels are AEIOU — 5 letters. In mixed coding, 5 symbols often map to vowels, rest to consonants. Think 5-finger rule: one hand for vowels.
• For alphabetical rank coding, think of it as a race: rearrange runners (letters) alphabetically and give them race bibs (1,2,3...), then report each runner's bib in the original starting order.

• SBI Clerk Prelims 2023 and 2024 had sentence-coding sets of 3-4 questions — mastering the CELI method alone can fetch you 3-4 marks in under 4 minutes.
• Letter-shift and opposite-letter questions are typically 1-mark individual questions — solve them in under 30 seconds each using the position shortcut.
• Conditional table-based coding appears more in Mains than Prelims — if it shows up in Prelims it is usually easier, do not overthink it.
• In Prelims, Coding-Decoding is usually difficulty level Easy to Medium — treat it as a scoring zone, not a challenge zone. Aim for 100 percent accuracy here.
• Always verify your logic with at least one given example before answering all questions in a set — one wrong assumption can cost you 4-5 marks.