I accept that the entropy (Shannon's) of a sum of positive numbers is the sum of the -P_n * LOG(P_n) for each number in the sum of numbers where P_n is the average contribution of a term. IE, if T = A + B, then S = -(A/T)*LOG(A/T) - (B/T)*LOG(B/T). But what about the entropy of A*B? Please don't respond with "why do it?", just give me some idea of how you might attempt to do it.