There are 204 squares on an eight-by-eight checkerboard.
64 1x1 squares,
49 2x2 squares,
36 3x3 squares,
25 4x4 squares ,
16 5x5 squares,
9 6x6 squares ,
4 7x7 squares,
1 8x8 square,
Hope this helps!
Forthfriend.
(PS: You should try searching the question before asking it, this has been asked and answered many times before.)