I can't figure out how i need to set up the equation in this problem.

The Japanese game of Tai Shogi is an expanded version of chess. Like chess, it is played on a square board covered with small squares. If each small square has a side length of 2 cm, the diagonal of the whole board measures

cm. How many squares are on the board?

Do i have to figure out the ares of the small squares (which is obviously 4) and then do something with that??

I'm not quite sure how to figure out the amount of individual squares.