1. The problem statement, all variables and given/known data Ten books are made into two piles. In how many ways can this be done if books as well as piles may or may not be distinguishable? 3. The attempt at a solution So I thought I'd try what I thought was the easiest case first, that being that neither the books nor the piles are distinguishable. In that case, can't the books only be arranged one way? I wouldn't be able to tell the difference between the books in the pile nor the piles themselves, so all combinations would be identical. Is that right?