An 8 by 8 checkerboard has alternating black and white squares. How many distinct squares, with sides on the grid lines of the checkerboard (horizontal and vertical) and containing at least 12 black squares, can be drawn on the checkerboard?
The only squares that can contain 12 black squares are squares with that are atleast 5 x 5.
In order to count the total number, we will count for the amount of 5 x 5 squares, 6 x 6 squares, 7 x 7 squares, and 8 x 8 squares.
Can you take it from here?