A chessboard consists of 64 small squares with a total area of 400 cm². If there is a border 3 cm wide surrounding the entire board, what is the length of one side of the chessboard including the border?

Explanation

The total area of the small squares is 400 cm², so the side length of the chessboard without the border is √400 = 20 cm. Adding the 3 cm border on each side adds 6 cm to the length, making the total side length 20 + 6 = 26 cm.