Calculate the area of a square if its side length is 9 dm.

Side length is equal to 9 dm.
Let’s define the area of the square. The area of a square is equal to the product of its sides of opposite sides. Since this is a square, it means that all sides of it are equal. We find the area.
S = a × a = a ^ 2 = 9 ^ 2 = 81 dm ^ 2.
This means that the area of a square with a side of 9 dm is 81 dm ^ 2.
Answer: S = 81 dm ^ 2.