My question is similar to this which I think is a part of my question. I hope I'm not creating a duplicate here.
There are 5 identical balls to be placed in the square boxes (3x3 grid). A box can contain one ball at a time. The five balls have to be placed in the squares in such a way that any row or column must contain at least one ball. There cannot be any row or column left vacant.
Find the number of ways this can be done.
I'm not able to find the total number of cases in which either a row or column is vacant.
Answer is 90 for this problem.