They provide various boxes or various objects. It also wants objects to be distributed into containers, so no container is empty. All we select k objects of r to keep no boxes empty, which (r C k) could be done. All such k artifacts can be placed in k containers, each of them in k! Forms. There will be remaining objects. All can be put in any of k boxes. Therefore, these objects could in the manner are organized. Consequently, both possible ways to do this are
Consequently, the number of ways that r objects in k different boxes can be arranged to make no book empty is every possible one