What is the perimetre of a square if it has an area of 81 cm2?

If I'm correct, the area of a square, or any rectangle (a square is also a rectangle) = side x side.

Since all sides of a square are = to each other, the area of a square = length of one side, squared.

So you'd need the square root of 81 to find the length of one side = 9. Perimeter of an object is the sum of it's sides. Square has 4 sides, so 9+9+9+9 = 36