Input-Output Questions for Placement 2026 (with Solutions)

Last Updated: March 2026

Introduction to Input-Output

Input-Output reasoning problems test your ability to understand and track patterns in data manipulation. In these questions, you're given an input line of words or numbers that undergoes a series of operations or steps to produce an output. Your task is to identify the underlying logic/rule and answer questions based on it. This topic is popular in TCS, Infosys, and Cognizant placement exams.

Why This Topic is Important

Input-Output questions assess:

Pattern recognition abilities
Step-by-step logical tracking
Data arrangement and rearrangement skills
Ability to work with multiple operations
Speed in identifying transformation rules

Companies That Ask Input-Output Questions (with Frequency)

Company	Frequency	Difficulty Level
TCS	High	Moderate to High
Infosys	High	Moderate
Wipro	Moderate	Moderate
Cognizant	Moderate	Moderate
Accenture	Low	Moderate
Capgemini	Low	Moderate
IBM	Low	Moderate
Tech Mahindra	Moderate	Easy to Moderate
HCL	Low	Moderate
LTI Mindtree	Low	Moderate

KEY FORMULAS / CONCEPTS

╔══════════════════════════════════════════════════════════════════╗
║                INPUT-OUTPUT PATTERN TYPES                        ║
╠══════════════════════════════════════════════════════════════════╣
║                                                                  ║
║  COMMON OPERATION TYPES                                          ║
║  ────────────────────────────────────────────────────────────   ║
║                                                                  ║
║  1. ARRANGEMENT PATTERNS                                         ║
║     - Ascending order arrangement                                ║
║     - Descending order arrangement                               ║
║     - Alternating (smallest-largest, 2nd smallest-2nd largest)   ║
║     - Vowel-first, then consonant                                ║
║     - Odd numbers first, then even                               ║
║                                                                  ║
║  2. SHIFTING PATTERNS                                            ║
║     - First element to last                                      ║
║     - Last element to first                                      ║
║     - Swap adjacent elements                                     ║
║     - Fixed position insertion                                   ║
║                                                                  ║
║  3. MATHEMATICAL OPERATIONS                                      ║
║     - Sum of digits placed first/last                            ║
║     - Product of digits                                          ║
║     - Difference between adjacent numbers                        ║
║     - Prime numbers first                                        ║
║                                                                  ║
║  4. WORD PATTERNS                                                ║
║     - Alphabetical order                                         ║
║     - Reverse alphabetical order                                 ║
║     - Length of word (shortest to longest)                       ║
║     - Number of vowels                                           ║
║     - Last letter alphabetical                                   ║
║                                                                  ║
║  GENERAL APPROACH                                                ║
║  ────────────────────────────────────────────────────────────   ║
║  Step 1: Observe Input and all given Steps                       ║
║  Step 2: Identify what changes between steps                     ║
║  Step 3: Determine the pattern/rule being applied                ║
║  Step 4: Verify pattern with subsequent steps                    ║
║  Step 5: Apply pattern to answer questions                       ║
║                                                                  ║
╚══════════════════════════════════════════════════════════════════╝

30 Practice Questions with Step-by-Step Solutions

Question 1-5 (Based on common pattern)

Input: 23 47 12 89 56 34 71

Step 1: 12 23 47 89 56 34 71 Step 2: 12 23 34 47 89 56 71 Step 3: 12 23 34 47 56 89 71 Step 4: 12 23 34 47 56 71 89

Pattern: Numbers are being arranged in ascending order, one number per step in its correct position.

Q1: How many steps are needed to complete the arrangement? Answer: 4 steps

Q2: What is the position of '56' in Step 2? Answer: 5th position

Q3: Which number is definitely at the 4th position in Step 3? Answer: 47

Q4: How many numbers are between 23 and 71 in the final step? Answer: 3 numbers (34, 47, 56)

Q5: Which step will have '34' at the 5th position? Answer: No step (34 is never at 5th position)

Question 6-10

Input: zebra apple mango banana cherry date

Step 1: apple zebra mango banana cherry date Step 2: apple banana zebra mango cherry date Step 3: apple banana cherry zebra mango date Step 4: apple banana cherry date zebra mango Step 5: apple banana cherry date mango zebra

Pattern: Words arranged alphabetically, one word per step from left.

Q6: How many steps to complete? Answer: 5 steps

Q7: What word is at 4th position in Step 3? Answer: zebra

Q8: In which step is 'cherry' at 3rd position? Answer: Step 3 and all subsequent steps

Q9: How many words are between 'apple' and 'date' in Step 4? Answer: 2 words (banana, cherry)

Q10: What is the position of 'mango' in the final step? Answer: 5th position

Question 11-15 (Complex Pattern)

Input: 45 82 17 63 91 28 54 76

Step 1: 17 45 82 63 91 28 54 76 Step 2: 17 91 45 82 63 28 54 76 Step 3: 17 91 28 45 82 63 54 76 Step 4: 17 91 28 82 45 63 54 76 Step 5: 17 91 28 82 54 45 63 76

Pattern: Smallest number first, then largest, then 2nd smallest, then 2nd largest, and so on (alternating min-max).

Q11: What is the pattern? Answer: Alternating ascending-descending selection

Q12: What will be Step 6? Answer: 17 91 28 82 54 76 45 63

Q13: Which number is at 5th position in Step 4? Answer: 45

Q14: How many steps to complete? Answer: 7 steps (until fully arranged)

Q15: What is the position of '63' in the final step? Answer: 7th position

Question 16-20 (Word Length Pattern)

Input: The quick brown fox jumps over lazy dog

Step 1: fox The quick brown jumps over lazy dog Step 2: fox dog The quick brown jumps over lazy Step 3: fox dog The lazy quick brown jumps over Step 4: fox dog The lazy over quick brown jumps Step 5: fox dog The lazy over brown quick jumps

Pattern: Words arranged by length (shortest first), within same length: alphabetical.

Q16: What is the basis of arrangement? Answer: Word length (ascending)

Q17: How many steps to complete? Answer: 8 steps (for 9 words)

Q18: Which word is at 3rd position in Step 3? Answer: The

Q19: In Step 4, which word is immediately before 'quick'? Answer: over

Q20: What is the final arrangement? Answer: fox dog The lazy over quick brown jumps

Question 21-25 (Reverse Pattern)

Input: 5 12 8 3 9 15 6 2

Step 1: 2 5 12 8 3 9 15 6 Step 2: 2 3 5 12 8 9 15 6 Step 3: 2 3 5 6 12 8 9 15 Step 4: 2 3 5 6 8 12 9 15 Step 5: 2 3 5 6 8 9 12 15

Pattern: Ascending order arrangement from left, one number fixed per step.

Q21: How many numbers change position in Step 3? Answer: 4 numbers

Q22: Which number is at the last position in Step 2? Answer: 6

Q23: In which step is '8' at 4th position? Answer: Step 4 (before final arrangement)

Q24: What is the sum of first and last numbers in Step 3? Answer: 2 + 15 = 17

Q25: Which number is fixed in its final position earliest? Answer: 2 and 15 (both in their positions by Step 5)

Question 26-30 (Mixed Pattern)

Input: 42 17 93 58 24 76 35 81

Step 1: 17 42 93 58 24 76 35 81 Step 2: 17 93 42 58 24 76 35 81 Step 3: 17 93 24 42 58 76 35 81 Step 4: 17 93 24 81 42 58 76 35 Step 5: 17 93 24 81 35 42 58 76

Pattern: Odd-positioned numbers in ascending, even-positioned numbers in descending (or alternating min-max from remaining).

Q26: Identify the pattern rule. Answer: Alternating selection of smallest and largest from remaining pool

Q27: What will Step 6 be? Answer: 17 93 24 81 35 76 42 58

Q28: Which number will be at position 6 in the final step? Answer: 58

Q29: How many total steps for complete arrangement? Answer: 7 steps

Q30: What is the position of '42' in Step 4? Answer: 5th position

SHORTCUTS & TRICKS

Trick 1: Identify Fixed Elements

Look for elements that don't move after a certain step - they're "fixed" in place.

Trick 2: Count Steps Formula

For arrangement problems: Maximum steps = (number of elements - 1) for simple sorting.

Trick 3: Position Tracking

Track specific elements through steps rather than rewriting entire arrangement.

Trick 4: Pattern Recognition

Common patterns:

Ascending/Descending
Alternating high-low
Vowel-Consonant separation
Odd-Even separation

Trick 5: Working Backwards

Sometimes it's easier to determine final arrangement first, then trace back.

Trick 6: Quick Verification

Always verify your identified pattern with at least 2-3 steps.

Trick 7: Skip Unnecessary Steps

Once pattern is clear, jump to required step directly without writing all intermediate steps.

Common Mistakes to Avoid

Not Identifying Pattern First: Always identify the pattern before answering questions.
Copy Errors: Be careful when rewriting arrangements - one error propagates through all steps.
Missing Multi-Step Changes: Sometimes multiple elements move in one step - don't assume only one changes.
Confusing Input with Step 1: Input is BEFORE any operations, Step 1 is after first operation.
Not Verifying Pattern: Always check your identified pattern works for all given steps.
Overlooking Same-Value Elements: When values are equal, alphabetical or original order might matter.
Rushing to Answer: Take time to understand the pattern fully before answering.

5 Frequently Asked Questions

Q1: How do I quickly identify the pattern? A: Compare Input with Step 1, then Step 1 with Step 2. Look for what changed and the rule governing the change.

Q2: What if the pattern isn't obvious? A: Check multiple aspects: numerical order, word length, alphabetical, vowels/consonants, odd/even, prime/composite.

Q3: Do I need to write all steps? A: No, once pattern is identified, you can jump to the required step or final arrangement directly.

Q4: How much time should I spend? A: 60-90 seconds for pattern identification + 10-15 seconds per question is reasonable.

Q5: Are there standard patterns I should memorize? A: Yes: Ascending, Descending, Alternate Min-Max, Vowel First, Odd-Even separation are most common.

Practice these 30 questions to master Input-Output reasoning for your placement exams!

Input Output Questions Placement