International Mathematical Olympiad

The International Mathematical Olympiad (IMO) is an annual six-problem, 42-point mathematical olympiad for pre-collegiate students and is the oldest of the International Science Olympiads. The first IMO was held in Romania in 1959. It has since been held annually, except in 1980. About 100 countries send teams of up to six students, plus one team leader, one deputy leader, and observers.