\sect{Baruch's A01.} Assume that the entropy S and the number of states in phase space ${\Omega}$ of a physical system are related through an arbitrary function, ${S=f\left(\Omega \right)}$. Show that the additive character of ${S}$ and the multiplicative character of ${\Omega}$ \emph{necessarily }require that ${f\left(\Omega \right ) \sim \ln \Omega}$. \\ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%