The formula for the number of multisets is (n k−1)! divided by a product of two other factorials. we want to use the quotient principle to explain why this formula counts multisets. the formula for the number of multisets is also a binomial coefficient, so it should have an interpretation that involves choosing k items from n k−1 items. the parts of the problem that follow lead us to these explanations. a. in how many ways can you place k red checkers and n−1 black checkers in a row?