Question

please explain it in detail

Answer 1

Let's say there are "n" rows.
Hence there are the same number, that is, "n" columns.

Thus total number of students in this arrangement is
${n}^{2}$
Now we find the closest perfect square to the given number of students, so that the least number of students are left out.

The number 540 lies between the following two perfect squares.

${23}^{2} = 529 \\ {24}^{2} = 576$
540 is clearly closer to the number 529. Thus there will be 23 rows and columns.

The number of students left out would be 540-529 = 11

Hence the answer is 11 students.