1. The problem statement, all variables and given/known data "A model system consists of N identical ”boxes” (e.g. quantum wells, atoms), each box with only two quantum levels, energies E0 = 0 and E1 = ε What is the number of microstates corresponding to the macrostate with total energy Mε?" 3. The attempt at a solution I've done questions like this in the past with a small number of quantum wells, but then I've simply counted the number of possible arrangements. For example, if you have 3 quantum wells with one particle in each, and each well has 4 energy levels (including E0=0), there are 10 different microstates if the macrostate energy is 3ε. But I can't find a general equation. Does anyone know the general equation(s) that are used to solve a question like this?