The perimeter of a square is the length of a one side multiplied by 4.
The diameter of the circle would be the length of the side of the square.
To find the length of the side/ diameter divide the total perimeter by 4:
Diameter = 36 / 4 = 8
To find the circumference of the circle, multiply the diameter by PI:
8 x PI = 25.13 units. Round the answer as needed.