SSC CGL Preparation – Day 9

Reasoning: Input-Output Reasoning

📌 What is Input-Output Reasoning?

Input-Output reasoning is a type of logical reasoning where a sequence of operations is applied step-by-step to transform an input into an output. The candidate must identify the logic or pattern used and apply it to solve questions.

This topic is common in banking exams but occasionally appears in SSC CGL, especially in advanced-level Reasoning sections.

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🧩 Types of Input-Output Questions:

1. Linear Arrangement-Based Rearrangement
   • Rearranging words/numbers based on alphabetical or numerical order.
   • Shifting elements from one end to another.
2. Mathematical Pattern-Based Operations
   • Numbers are processed through mathematical functions in steps.
   • Usually involves square, multiplication, addition, subtraction, or prime factor logic.
3. Letter-Word Pattern Logic
   • Letters shifted based on positions (A = 1, B = 2, etc.)
   • Rearranging based on vowels/consonants, dictionary order, etc.

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🔍 Key Identifiers in the Question:

• Input: The initial set of elements.
• Steps: The transformation stages.
• Final Output: The last step when the pattern completes.

You’re often asked:

• What is Step 3?
• How many steps required to reach the output?
• What is the 4th element in Step 2?
• What would be the output for a new input?

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✅ General Strategy to Solve Input-Output Questions:

1. Analyze the steps carefully.
   • Compare consecutive steps and observe how elements change.
2. Note the position & movement.
   • Is the largest/smallest number moving to the start/end?
   • Are words rearranged in alphabetical order?
3. Detect consistency in transformation.
   • Is the same rule applied across steps?
4. Replicate the logic.
   • Apply the same pattern to a fresh input.

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📘 Example 1: Word Arrangement

Input: ball kite fan orange jug net
Step I: kite ball fan orange jug net
Step II: kite orange ball fan jug net
Step III: kite orange jug ball fan net
Step IV: kite orange jug net ball fan

🔍 Observation:
Words are arranged alphabetically from left. First “kite”, then “orange”, then “jug”, etc.

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📗 Example 2: Number Rearrangement

Input: 65 42 89 24 16
Step I: 16 65 42 89 24
Step II: 16 24 65 42 89
Step III: 16 24 42 65 89

🔍 Observation:
Numbers are being arranged in ascending order, one element per step.

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📙 Example 3: Mathematical Pattern

Input: 2 3 4 5 6
Step I: 4 6 8 10 12
Step II: 12 10 8 6 4

🔍 Explanation:

• Step I: Each number doubled.
• Step II: Reversed order.

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⚠️ Common Traps to Avoid

• Don’t assume the logic without checking all steps.
• Look out for shifting patterns vs. swapping patterns.
• Pay attention to whether the transformation is happening left to right or right to left.

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🛠️ Practice Method

• Start with examples given in the question.
• Try to create a flowchart of steps.
• Practice with mixed inputs (numbers + words).
• Track number of elements moved per step.

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💡 Tips for SSC CGL

• Though not asked very frequently, these questions can appear in advanced-level sets.
• Practice 3–5 sets before the exam for familiarity.
• Focus more on spotting systematic transformations.