Nearest perfect square (or fourth power) to a given number

This type of question, asked 2 times: CDS 1 2018, CDS 1 2022. All 3 questions below, oldest first.

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Question 1
CDS 1 2018
12 $The smallest integer with 4 digits which is a perfect square is$
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Question 2
CDS 1 2022
20 $What is the smallest natural number from the following which must be subtracted from 9410 to make the remaining number a perfect square?$
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Question 3
CDS 1 2022
16 $n$
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