Data Interpretation & Logical Reasoning / Short-form reasoning

Input and Output

Input and Output: concepts, worked examples and practice.

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Start with the basics

Input and Output, explained simply

Input-output problems show a process changing a list in stages. Track what moves or changes at each stage.

Try a small example

A machine sorts 4, 1, 3 into increasing order. What is its final output?

Show the steps

Find the smallest number: 1.
Place 3 next and 4 last.
The output is 1, 3, 4.

Remember: Do not assume sorting is the rule unless the shown stages support it.

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Stepwise Rearrangement

Track what each machine step fixes and what remains unfixed. Apply only the movement shown in the examples.

Worked example

A rule moves the smallest remaining number to the left at each step. From 8 3 6 1, the first step is 1 8 3 6 and the second is 1 3 8 6.

Exam focus

MAT: Intelligence and Critical Reasoning

Use diagrams for relationships and distinguish logical necessity from everyday plausibility.

NMAT: Logical Reasoning

Test assumptions and deductions, then use small structured cases for puzzles and input-output rules.

SNAP: Analytical and Logical Reasoning

Use compact diagrams, clear direction conventions and quick elimination. Skip long uncertain branches and return later.

Check your understanding

Explain the idea in your own words before opening the answer. Then apply it to the example.

Stepwise Rearrangement

Explain the main rule in stepwise rearrangement, then apply it to a small example. State the assumption that makes your reasoning valid.

Review the note

Check your answer

Track what each machine step fixes and what remains unfixed. Apply only the movement shown in the examples.

Worked example: A rule moves the smallest remaining number to the left at each step. From 8 3 6 1, the first step is 1 8 3 6 and the second is 1 3 8 6.

Rule Detection

Explain the main rule in rule detection, then apply it to a small example. State the assumption that makes your reasoning valid.

Review the note

Check your answer

Check whether a machine sorts numbers, words, positions or alternating categories. Verify a rule across more than one transition.

Worked example: If step one places the smallest number left and step two places the alphabetically last word right, continue the alternating rule. Sorting the whole list numerically would ignore half the evidence.

Practice questions

Bharatiya Pathshala

Opening preparation notes...

BEGINNER

Input and Output: visual worked lesson

Core idea

Input-output problems show a process changing a list in stages. Track what moves or changes at each stage.

Solving method

Compare consecutive steps and identify what changes and what remains fixed. Test a proposed rule on a later step before predicting the output.

Worked example

A machine sorts 4, 1, 3 into increasing order. What is its final output? 1. Find the smallest number: 1. 2. Place 3 next and 4 last. 3. The output is 1, 3, 4.

Read the diagram

The example explicitly asks for increasing order. One possible intermediate step places the smallest number first, followed by the remaining reordering. Other sorting processes could reach the same output using different steps. In a real input-output question, infer the process from all shown stages before predicting a missing stage.

Exam-style application

Input: 42 17 63 25. Step 1: 17 42 63 25. Step 2: 17 25 42 63. Rule: move the smallest remaining number into the next position from the left, preserving the order of the others. Applying it to 31 12 24 9 gives step 1: 9 31 12 24; step 2: 9 12 31 24; step 3: 9 12 24 31.

Common mistakes

Do not assume sorting is the rule unless the shown stages support it. The number of rearrangements depends on the specified machine. A sorting rule cannot be assumed solely from a sorted final output.

One possible increasing-order sorting process. The illustration assumes an increasing-sort rule; it does not infer a rule from one row. — One possible increasing-order sorting process

The illustration assumes an increasing-sort rule; it does not infer a rule from one row. — One possible increasing-order sorting process

Source record: Bharatiya Pathshala — original illustrated lessons.

Input and Output, explained simply

Try a small example

Stepwise Rearrangement

Worked example

MAT: Intelligence and Critical Reasoning

NMAT: Logical Reasoning

SNAP: Analytical and Logical Reasoning

Check your understanding

Stepwise Rearrangement

Rule Detection

Input and Output, explained simply

Try a small example

Input and Output: visual worked lesson

Core idea

Solving method

Worked example

Read the diagram

Exam-style application

Common mistakes

Stepwise Rearrangement

Worked example

Rule Detection

Worked example

Application and strategy

Worked application

Common traps and strategy

MAT: Intelligence and Critical Reasoning

NMAT: Logical Reasoning

SNAP: Analytical and Logical Reasoning

Check your understanding

Stepwise Rearrangement

Rule Detection

Input and Output: visual worked lesson

Core idea

Solving method

Worked example

Read the diagram

Exam-style application

Common mistakes

Rule Detection

Worked example

Application and strategy

Worked application

Common traps and strategy