Let $K_1=\Bbb Q(\sqrt{d_1})$ , $K_2=\Bbb Q(\sqrt{d_2})$ and $K=\Bbb Q(\sqrt{d_1},\sqrt{d_2})$.Suppose $h_1,h_2,h$ be class number of $K_1,K_2,K$ respectively.

(i) Can we express $h$ in terms of $h_1,h_2$?

(ii) Knowing the divisibility properties of $h_1,h_2$, I want help with concluding about the divisibility of $h_1,h_2.$