Nearest perfect square: least to add, least n-digit square, side of a square formation

This type of question, asked 3 times: 17 Sep 2025 S3, 19 Sep 2025 S2, 21 Sep 2025 S1. All 3 questions below, oldest first.

Try each one first, then open its answer.

Question 1
17 Sep 2025 S3
51 $A gardener organizes plants into rows to create a square formation but discovers that 15 plants are not included. If the total number of plants is 3984, then what is the number of plants in each row?$
Tap an option to check your answer.
Question 2
19 Sep 2025 S2
52 $Which of the following is the least 6-digit number, which is a perfect square?$
Tap an option to check your answer.
Question 3
21 Sep 2025 S1
51 $What is the smallest number that must be added to 2378 to make it a perfect square?$
Tap an option to check your answer.

Question 1