Equidistribution of divergent orbits and continued fraction expansion of rationals

We establish an equidistribution result for push-forwards of certain locally finite algebraic measures in the adelic extension of the space of lattices in the plane. As an application of our analysis we obtain new results regarding the asymptotic normality of the continued fraction expansions of most rationals with a high denominator as well as an estimate on the length of their continued fraction expansions. By similar methods we also establish a complementary result to Zaremba’s conjecture. Namely, we show that given a bound M, for any large q, the number of rationals $p\mathrm{/}q\in [0,1]$ for which the coefficients of the continued fraction expansion of p/q are bounded by M is $o(q^{1-ϵ})$ for some $ϵ>0$ which depends on M.