1. The problem statement, all variables and given/known data Say you have 5 identical balls. You want to put them into 4 different boxes. What is the total number of ways the balls can be arranged? For example, you could have all 5 balls in one box. You could have 3 balls in one box and 2 balls in another, etc. 2. Relevant equations 3. The attempt at a solution Since the balls are identical, order doesn't matter and this is a combination. So I drew it out, and figured out the correct number of ways - basically by doing a tree diagram. But what I'm actually trying to figure out is what the equation looks like. I want to generalize it so that it works for m boxes and n balls, so I thought I'd make up a more concrete example to help me.