A white square and a black square have to be chosen on a chessboard such that they do not lie in the same row or column or diagonal. In how many ways can they be chosen.
My approach:-
Ways of choosing 1 white square =32c1
Ways of choosing a black square such that it is not in same row, column or diagonal would be (32-(4+4))=24c1
now answer should be (32c1 * 24c1)/2 = 768/2 = 384 --->Reason for dividing by 2 is that while doing 32c1 * 24c1 we have done ordering like suppose a white square chosen was e4 and the black square chosen was g5 so while doing 32c1 * 24c1..
I have counted cases of e4 g5 and g5 e4 as separate, hence need to adjust that overcounting.
But according to the answer given in the book, its 768 only