Heres the question:
What is the largest number of squares on an 8 $\times$8 checkerboard which can be colored green,so that in any one arrangement of three squares ("tromino"),at least one square is not colored green?
Here's what i have done:
if we divide the square into $ 2 \times 2 $ squares and we take 1 square out of each $ 2 \times 2 $ block then we have a total of 16 green squares.But this answer is wrong.can anyone point out the error here?