Maybe a simple question here but I was wondering how $\int \, dn=N$?
I understand if you integrate say 1 in terms of $X$ you get $X$ but if you integrate $0$ how does that equal $X$ or $N$ in this case.
To give you further context I am doing this question. I got it right but I guessed which is never good because I don't see how integrating nothing gets me that.
Here is what the Mark Scheme says:
$$\int_0^N dn=\int_0^N (1) dn=\int_0^N (n^0) dn=\left[n^1/1\right]^N_0=N-0=N$$