1. The problem statement, all variables and given/known data Explain why the number of microstates W in Boltzmanns principle, is W = ƩNi! / ∏Ni! when i ideal gasses are mixed at constant volume and temperature. Ni is the number of particles of component i. 2. Relevant equations S=klnW , where W is the number of microstates and k is Boltzmanns constant. 3. The attempt at a solution What I am really asking here, is an explanation on how the microstates are counted. It is obviously the sum of all the factorials divided by the product of all the factorials of the different components. What is the logic behind this?