Questions
3 questions per paper
Difficulty
Medium
Importance
High yield for SSC and Banking selection
Overview
Coding-Decoding tests an aspirant's analytical ability to identify patterns within scrambled words, numbers, or symbols. It is a high-scoring pillar of the Reasoning section in SSC, Banking, and Police exams, requiring rapid pattern recognition and meticulous attention to detail under strict time constraints.
Letter Coding
This subtopic involves transforming letters based on a fixed logic, such as forward/backward shifts, reverse alphabets, or positional swaps. Success hinges on immediate visualization of A-Z positions and their corresponding numerical values.
- Memorize EJOTY rule for quick positional retrieval
- Master the sum of opposite pairs which is always 27
- Always check for +n, -n sequences in consecutive positions
- Look for vowel-consonant segregation patterns
- Consider circular arrangement shifts where A follows Z
Number Coding
In number coding, letters are replaced by specific digits, or a word is assigned a numerical value based on the sum or product of its letter positions. It requires high speed in basic arithmetic and understanding of place-value logic.
- Sum of alphabetical positions of letters
- Multiplication or addition of position numbers
- Constant digit assignment for specific letters
- Reverse positional value application
- Digital sum reduction of word totals
Substitution Coding
Also known as direct coding, this method replaces common terms with 'code names' (e.g., 'Pen' is called 'Book'). The key is to avoid interpreting the code literally and instead strictly follow the defined renaming logic.
- Read the final question first to identify target word
- Identify the specific substitution rule given in the prompt
- Ignore real-world logic; prioritize the conditional definition
- Map the direct replacement consistently throughout the set
Mathematical Operations (Symbol Substitution)
This involves replacing standard arithmetic operators (+, -, *, /) with symbols like '>', '<', or 'a', 'b'. It tests the candidate's ability to apply the BODMAS rule while simultaneously managing the logic of symbol replacement.
- Strict adherence to BODMAS/PEMDAS sequence
- Rewrite the entire expression with replaced operators before solving
- Watch for bracket placement affecting priority
- Test individual options rapidly using the elimination method
Formula Sheet
A=1, B=2, ..., Z=26
Opposite pair sum: Position(L) + Position(Reverse L) = 27
BODMAS: Brackets, Orders, Division, Multiplication, Addition, Subtraction
Exam Tip
Write A-Z with numbers 1-26 and Z-A with 26-1 on your rough sheet immediately after the test starts to eliminate calculation errors during high-speed solving.
Common Mistakes
- Mistaking the forward shift pattern for a reverse shift pattern during the stress of the exam
- Forgetting to apply BODMAS when evaluating symbol-substituted mathematical expressions
- Over-relying on real-world associations in substitution coding instead of following the provided definitions
More Revision Notes
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