The competitions in Norway started in 1921 but was discontinued in mid 1970s.
The competition got today’s format in 1985. The Niels Henrik Abels mathematical competition is held in three rounds. The first consists of 20 multiple-choice questions, the second round has 10 problems to which the students have to provide final answer (an integer between 0 and 999), and the final round consists of 4 olympiad-style problems.
More information can be found on the official page.
Norway at International Competitions
Students from Norway regularly participate at the International Mathematical Olympiad, The Nordic Mathematical Competition and the Baltic Way.