Kuroda's formula and arithmetic statistics

Kuroda’s formula relates the class number of a multi-quadratic number field $K$ to the class numbers of its quadratic subfields $k_i$. A key component in this formula is the unit group index $Q(K) = [$\mathcal{O}${K}^{\times}: \prod_i$\mathcal{O}${k_i}^{\times}]$\mathrm{.}Westudyhow$Q(K)$ behaves on average in certain natural families of totally real biquadratic fields $K$ parametrized by prime numbers.