Archimedes's cattle problem
Archimedes's cattle problem (or the problema bovinum or problema Archimedis) is a problem in Diophantine analysis, the study of polynomial equations with integer solutions. Attributed to Archimedes, the problem involves computing the number of cattle in a herd of the sun god from a given set of restrictions.
Source: Wikipedia — Archimedes's cattle problem (CC BY-SA 4.0)