Ok, for the sake of generalization I am going to let the starting set be
$$S_0$$
$$For\ the\ sets\ S_i\ where\ i,j = 0,1,2,...,n\ and\ s_i \in S_i\ where\ s_i \in \mathbb{N}.$$
$$S_i \cap S_j = \emptyset,\ for\ any\ and\ all\ considered\ sets,$$
$$and\ |S_0| = |S_1| = |S_2|...|S_i| = M\ where\ M\ is\ the\ cardinality\ of\ any\ set\ S_i.$$
$$In\ addition,\ for\ all\ sets,\ S_i\ =\ \left\{i, i+1, i+2,...,i+M - 1\right\}. $$
$$Let\ x \in \mathbb{N},$$$$\ x \in S_i\ if\ and\ only\ if$$
$$x/M = i + k/M\ where\ k\ is\ the\ remainder\ of\ the\ quotient.$$
So, by your example, x will belong to $S_0$ if $x/4\ =\ 0 + j/4,\ where\ 0\ \leq\ j\ < 4.$
Here are some more examples to try and express my point:
$$x = 10$$ $$x/4 = 2 + 2/4$$
$$x = 10\ is\ a\ member\ of\ the\ set\ S_2\ as\ i = 2.$$
If there are any suggestions or errors in this argument please comment, I am quite new at this.