Answer:
36 rectangles
Explanation:
Assuming that all you are asking for is the individual number of squares (not the number of squares and rectangles that can be made when combining the individual ones), the answer is 36.
We get this by multiplying the six squares on one side by the six on the other side. This allows us to calculate the total number! You can do this on a calculator or by hand.
However, if you would like the TOTAL number of rectangles that includes combining the individual ones, this chessboard would have 91 squares and 441 rectangles.