The area of a square is calculated by the formula:
Area = side length ^2
Here, we're given the area to be 400 square centimeters and we are asked to find the length of the side.
To calculate this, we can rearrange the formula to solve for side length:
Side length = Square root of the Area
So, to find the length of the side of our chess board, we take the square root of the area (which is 400). The square root of 400 is 20.
Therefore, the side length of the chess board is 20 cm.