Figure out that Quantum Number

Relevant wiki: Electron Configurations

We know that the Angular Quantum Numbers range from $0$ to $n-1$ , where $n$ is the Principle Quantum number. That is, when $n=n$ :

$l=1,2,3,\cdots ,(n-1)$

But we know that the Principle Quantum Number of an electron in the $\text N$ shell $=4$ . Thus the set of all possible Angular Quantum Numbers would be:

$l =0,1,2,3$

Thus there are $4$ Angular Quantum Numbers at this state.