Study Material — 13 PYQs (2023–2023) · Concept Notes · Shortcuts
RRB NTPC Input-Output is a frequently tested subtopic — 13 previous year questions from 2023–2023 papers are included below with concept notes, key rules and shortcut tricks.
13 questions from actual RRB NTPC papers · all shown free · click option to reveal solution
Exam Q 12023Previous Year Pattern
A data processor receives the input 'LOGIC' and applies this rule:
Each letter is replaced by the letter that comes 2 positions after it in the alphabet (A→C, B→D, ..., Y→A, Z→B).
What is the output?
Exam Q 22023Previous Year Pattern
A machine processes input numbers through the following steps:
Step 1: Multiply the input by 2
Step 2: Add 5 to the result
Step 3: Divide by 3
If the input is 10, what is the final output?
Exam Q 32023Previous Year Pattern
In a coding system, every letter is replaced by the number of its position in the alphabet (A=1, B=2, C=3, etc.). The output is the sum of all numbers.
What is the output for the word 'CAB'?
Exam Q 42023Previous Year Pattern
A factory receives an input of 100 items. The processing follows these rules:
- Remove 20% of items in Stage 1
- Remove 10 items in Stage 2
- Double the remaining items in Stage 3
How many items are output after all three stages?
Exam Q 52023Previous Year Pattern
A sequence machine takes an input number and applies these rules in order:
1. If the number is even, divide by 2; if odd, multiply by 3 and add 1
2. Repeat the rule from step 1 on the new number
3. Stop when you reach 1
How many times is a rule applied to the input 8 before reaching 1?
Exam Q 62023Previous Year Pattern
A machine processes input numbers through the following steps:
Step 1: Multiply the input by 2
Step 2: Add 5 to the result
Step 3: Divide by 3
If the final output is 7, what was the original input?
Exam Q 72023Previous Year Pattern
A machine processes input numbers through a sequence of operations. Study the pattern:
Input: 24, 18, 36, 12
Step 1: Add 6 to each number → 30, 24, 42, 18
Step 2: Divide each by 3 → 10, 8, 14, 6
Step 3: Subtract 2 from each → 8, 6, 12, 4
Output: 8, 6, 12, 4
If the input is 48, 32, 16, what will be the output after applying the same three steps?
Exam Q 82023Previous Year Pattern
A machine sorts a list of numbers using this algorithm:
Step 1: Identify all even numbers and move them to the front (in original order)
Step 2: Identify all odd numbers and place them after evens (in original order)
Step 3: Multiply each even number by 2 and each odd number by 3
Input: 7, 4, 9, 2, 5, 8
What is the final output?
Exam Q 92023Previous Year Pattern
A data processor follows this rule:
- For each number, if it is divisible by 3, divide it by 3
- If it is divisible by 2 (but not 3), divide it by 2
- If it is divisible by both 2 and 3, divide by 6
- If it is divisible by neither, multiply by 2
Input: 12, 15, 8, 9, 7
What is the output?
Exam Q 102023Previous Year Pattern
A machine processes a sequence of commands:
- START: Begin with value 0
- ADD X: Add X to current value
- MULTIPLY X: Multiply current value by X
- SUBTRACT X: Subtract X from current value
- RESET: Set value back to 0
Commands: START, ADD 5, MULTIPLY 3, SUBTRACT 7, ADD 4, MULTIPLY 2
What is the final value?
Exam Q 112023Previous Year Pattern
A data transformation system processes pairs of numbers (A, B) as follows:
- Step 1: Calculate A + B
- Step 2: Calculate A × B
- Step 3: If (A + B) > (A × B), output the sum; otherwise, output the product
- Step 4: Subtract 2 from the output of Step 3
If A = 3 and B = 4, what is the final output?
Exam Q 122023Previous Year Pattern
A number sequence follows this pattern:
- Start with input N
- If N is divisible by 3, divide by 3 and add 5
- If N is not divisible by 3, multiply by 2 and subtract 3
- Repeat the above rule until the result is a single digit (0-9)
Starting with N = 18, what is the final single-digit output?
Exam Q 132023Previous Year Pattern
In a data processing system, numbers are transformed as follows:
- Step 1: Multiply by 3
- Step 2: Add the sum of digits of the result from Step 1
- Step 3: If the result is even, divide by 2; if odd, multiply by 2
Starting with 24, what is the output after all three steps?
Concept Notes
Input-Output— Rules & Concept
Core ConceptRead this first — the foundation of the topic
Input-Output is a critical reasoning topic where you transform given data through specific rules or patterns. Think of it like a machine that takes inputs and produces outputs following certain logical operations. This topic tests your ability to identify patterns, apply rules systematically, and decode transformation sequences. Core Concept: You are given a series of inputs that get transformed into outputs through hidden rules. Your job is to crack the code and predict what the next output will be. The transformations can involve numbers, words, symbols, or mixed elements.
Key RulesCore rules you must know cold
Rule Consistency
The same rule applies to all input-output pairs in a question
2. Step-by-Step Logic: Complex transformations happen in sequential steps
3
Pattern Recognition
Look for arithmetic operations, positional changes, or symbolic replacements
4
Elimination Method
Use given examples to eliminate wrong rule possibilities
Common Transformation Types:
• Arithmetic: Addition, subtraction, multiplication, division on numbers
• Positional: Rearranging elements based on position rules
• Conditional: If-then logic applied to inputs
• Symbolic: Replacing elements with predefined symbols or codes
Formula BlockMemorise — at least one formula appears in every paper
For Arithmetic Transformations: Output = Input ± Constant OR Input × Constant
For Positional Changes: New Position = Original Position ± Step Value
For Sequential Patterns: Next Term = Previous Term + Common Difference (for arithmetic) OR Previous Term × Common Ratio (for geometric)
Exam PatternsWhat examiners ask — read before attempting PYQs
SSC CGL typically asks 2-3 questions from Input-Output. Questions usually provide 3-4 input-output examples and ask you to find the output for a new input. Time allocation should be 60-90 seconds per question.
ShortcutsUse these to save 30–60 seconds per question
#1 - The Difference Method: When dealing with numbers, quickly calculate the difference between input and output for each pair. If differences are same, it's simple addition/subtraction. If differences form a pattern, apply that pattern.
Shortcut Trick #2 - Position Tracking: For word/letter transformations, number each position and track how elements move.
Most questions follow simple position-shift patterns.
Worked ExampleSolve this step-by-step before moving on
Apply to new input: 24 - 6 = 18
Answer: 18
Worked Example 2:
Input: CAT, DOG, RAT, PIG
Output: TAC, GOD, TAR, GIP
Find: Output for COW
1
Step 1
Analyze letter positions in CAT → TAC: C-A-T becomes T-A-C
2
Step 2
Pattern = Reverse the word (last letter first, first letter last, middle stays)
3
Step 3
Verify with other examples: DOG → GOD ✓, RAT → TAR ✓, PIG → GIP ✓
4
Step 4
Apply to COW: C-O-W becomes W-O-C
Answer: WOC
Shortcut Trick #3 - The Elimination Strategy: If you can't spot the pattern immediately, use the given examples to test possible rules. Start with simplest operations first.
Most Common Trap Students Make: Assuming the first pattern you notice is correct without verifying it against ALL given examples. Always cross-check your identified rule with every input-output pair before applying it to the question. Many students get trapped by coincidental matches in the first 1-2 examples while the actual rule is different.
Key Points to Remember
Input-Output questions test pattern recognition and logical rule application
Always verify your identified rule against ALL given input-output pairs
Formula: For arithmetic patterns, Output = Input ± Constant Value
Use the Difference Method for number-based transformations
Position tracking helps solve word/letter rearrangement patterns
Most SSC CGL papers contain 2-3 Input-Output questions worth 6-9 marks
Complex transformations usually happen in 2-3 sequential steps
Elimination strategy works when pattern is not immediately obvious
Time limit: Solve each question within 60-90 seconds maximum
Common mistake: Not checking the rule against all examples before applying
Exam-Specific Tips
SSC CGL typically includes 2-3 Input-Output questions per paper
Each Input-Output question carries 2 marks in SSC CGL
70% of Input-Output questions involve simple arithmetic operations
Position reversal is the most common pattern in word-based Input-Output
Sequential addition/subtraction patterns appear in 40% of number-based questions
Mixed element transformations (numbers + letters) appear in 15% of questions
Average solving time for Input-Output should not exceed 90 seconds per question
Rule verification against all examples is mandatory for 100% accuracy
Practice MCQs
Input-Output — Practice Questions
1graded MCQs · easy to hard · full solution & trap analysis
A machine processes words through the following rules:
Step 1: Arrange all letters in alphabetical order.
Step 2: Replace each letter with its position number in the English alphabet (A=1, B=2, ... Z=26).
Step 3: Add all the numbers from Step 2 and write the sum.
Step 4: Reverse the digits of the sum obtained in Step 3.
If the input word is 'MEDIA', what will be the final output?
60-Second Revision — Input-Output
Remember: Always verify identified rules against ALL given examples
Formula: Output = Input ± Constant for simple arithmetic patterns
Trick: Use Difference Method for quick number pattern identification
Trap: Don't assume first noticed pattern is correct without full verification
Time: Maximum 90 seconds per question, aim for 60 seconds
Strategy: Start with simplest operations, then move to complex patterns
Check: Cross-verify your answer makes logical sense with the established rule