I recently got introduced to the Statistical Mechanics, particularly, the Statistical Interpretation of Entropy and am utterly confused regarding the following problem:
Imagine a box with two identical compartments. Then a crude specification of the position of a molecule of a gas will be whether it's located in the left or the right compartment of the box. Any molecule is equally likely to be in either of the compartments.
Assume that there are $N$ 'identical' molecules.
Consider the macrostate with $n_1$ = $k$ and $n_2$ = $N-k$. Here, $n_1$ refers to the number of molecules in the left compartment and $n_2$ to the number of molecules in the right compartment.
Then the number of microstates corresponding to this macrostate should be 1 (since all the particles are identical).
But, in all the resources I've referred to, I found the number of microstate(s) corresponding to this macrostate to be $\frac{N!}{n_1! n_2!}$.
Kindly throw some light onto this conceptual flaw.