Why can we say that the charge of any body is always an integral multiple of $e$?

(N/A) The fundamental charges in the universe are protons and electrons,each having a magnitude of $e$.
Since any body is composed of a discrete number of these particles,the total charge $q$ on a body is the algebraic sum of the charges of its constituent protons and electrons.
If a body contains $n_2$ protons and $n_1$ electrons,the total charge is $q = n_2(e) + n_1(-e) = (n_2 - n_1)e$.
Let $n = (n_2 - n_1)$,where $n$ is an integer (positive,negative,or zero).
Therefore,$q = ne$.
This property is known as the quantization of charge,which states that the charge on any body is always an integral multiple of the elementary charge $e$.