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Input-output practice questions for bank exams

By the PrepMatic team · Updated 9 Oct 2026 · 3 min read

In an input-output question, a machine rearranges a line of numbers or words step by step by a fixed rule. You get the input and the steps shown, work out the rule, and then answer questions about a given step or a new input. Input-output is usually a mains-level reasoning topic, and a set takes under six minutes once you spot the rule early.

How the machine works

For the machine in this page, the rule alternates between the two ends of the line.

• Step I: the largest number moves to the extreme left.
• Step II: the smallest number moves to the extreme right.
• Step III: the second-largest number moves to the second position from the left.
• Step IV: the second-smallest number moves to the second position from the right.
• The pattern continues, one number per step, until the numbers are in descending order. The other numbers keep their relative order.

Input: 48 15 73 29 91 36 62

Step I: 91 48 15 73 29 36 62

Step II: 91 48 73 29 36 62 15

Step III: 91 73 48 29 36 62 15

Step IV: 91 73 48 36 62 29 15

Step V: 91 73 62 48 36 29 15

Five practice questions

Question 1

For the same input, what is Step II?

• A. 91 48 15 73 29 36 62
• B. 91 73 48 29 36 62 15
• C. 91 48 73 36 29 62 15
• D. 91 48 73 29 36 62 15

Question 2

Which number is fourth from the left in Step III?

• A. 36
• B. 48
• C. 29
• D. 62

Question 3

How many steps are needed to reach the final arrangement for this input?

• A. 5
• B. 6
• C. 7
• D. 8

Question 4

For the new input 35 82 14 67 49 23 58, which number is fifth from the left in Step IV?

• A. 49
• B. 58
• C. 23
• D. 35

Question 5

In Step IV of the original input, what is the sum of the second number from the left and the second number from the right?

• A. 98
• B. 109
• C. 102
• D. 88

Answers and explanations

1. D. Step I gives 91 48 15 73 29 36 62. In Step II the smallest number, 15, moves to the right end, and the others keep their order: 91 48 73 29 36 62 15.
2. C. Step III is 91 73 48 29 36 62 15, since 73 (the second-largest) moves to the second place. The fourth number from the left is 29.
3. A. Each step fixes one more number. By Step V the line reads 91 73 62 48 36 29 15, which is in descending order, so five steps are needed.
4. B. For the input 35 82 14 67 49 23 58: Step I is 82 35 14 67 49 23 58. Step II is 82 35 67 49 23 58 14. Step III is 82 67 35 49 23 58 14. Step IV is 82 67 35 49 58 23 14, with 23 as the second-smallest moving to the second place from the right. The fifth number from the left is 58.
5. C. Step IV of the original input is 91 73 48 36 62 29 15. The second number from the left is 73 and the second from the right is 29, so the sum is 73 + 29 = 102.

How to prepare input-output

• Compare the input with Step I, and Step I with Step II. Ask what moved and where. The rule usually shows itself in the first two steps.
• Check for two rules working together. Many mains sets alternate between two operations, as here, or combine a number rule with a word rule.
• Write the final arrangement early. In a sorting machine, you know the last step already (sorted order), so you can count the steps.
• Do not compute steps you do not need. If a question asks for Step IV, write only up to Step IV.
• Look at the word-and-number versions. Some sets sort words alphabetically on one side and numbers on the other, but the method is the same.
• Re-check against the printed steps. Apply your rule to the given steps; if every step matches, you have the rule.

Allow 60 seconds to find the rule and 30 seconds per question. For another rule-finding skill, see coding-decoding.

The full input-output topic test is on PrepMatic (about 15 questions, 30 minutes). The Reasoning Ability guide and the bank exam hub show how this topic fits each exam.

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