Hurwitz's theorem (number theory)
In number theory, Hurwitz's theorem, named after Adolf Hurwitz, gives a bound on a Diophantine approximation. The theorem states that for every irrational number ξ there are infinitely many relatively prime integers m, n such that | ξ − m n | < 1 5 n 2 .
Source: Wikipedia — Hurwitz's theorem (number theory) (CC BY-SA 4.0)