A square has an area of 100 in ^2. What is the perimeter of the square

Area of a square is its side length squared ...

A=s^2 solving for s ...

s=√A

The perimeter of a square is 4 times its side length ...

P=4s, and since s=√A

P=4√A, and we are told that A=100 in^2 so

P=4√100

P=4*10

P=40 in