NIMO Monthly Contest Rules

Last updated May 2016.


Monthly contest participants must be entering grade 12 or below (or equivalent) in the current school year, and must be at most 19 years old on January 1 of the current school year. Those who do not fall within the given age and grade ranges may participate unofficially. Participants may not discuss problems with anyone during the contest period. NIMO may ban individuals caught cheating on contests.

Contest Format

Monthly contests will usually have 8 problems to solve in 40 minutes. The format of the contest will be announced well before the contest begins, and in particular can be seen from the web interface. All answers are positive integers.

Permitted Materials

No aids other than scratch paper, graph paper, rulers, compasses, and protractors may be used. Computers are permitted only for viewing contest problems, submitting answers, skipping to a different problem, or viewing the live scoreboard.


Each problem has a given weight (announced before the contest), and a contestant's score is the sum of the weights of the problems she scores correctly. At most 3 submissions are allowed per problem per contestant. Only the latest submission for a given problem will be graded. Contestants are ranked in decreasing order of total score (higher score is better), and ties are broken by comparing penalties. Each contestant's penalty is 0 at the start of the contest, and for each correct problem, the sum of the time for the correct submission plus 20 minutes per incorrect submission is added to the penalty. Note that if a contestant does not correctly solve a problem, the problem does not contribute to her penalty. (For some contests, there may also be a penalty for incorrect final submissions to a problem.)

These parameters may vary based on the contest. Any changes from the values specified here will be announced well in advance. They will also be viewable on the Contests & Rules page under "More Details" once the contest is posted.

As of the 2016-2017 academic calendar year, prizes have been discontinued.