Let T = (V, E) be a rooted tree ordered by a universal address system, (a) If

Question:

Let T = (V, E) be a rooted tree ordered by a universal address system,
(a) If vertex v in T has address 2.1.3.6, what is the smallest number of siblings that v must have?
(b) For the vertex v in part (a), find the address of its parent,
(c) How many ancestors does the vertex v in part (a) have?
(d) With the presence of v in T, what other addresses must there be in the system?