There are several types of rounds in ABMC. All rounds are in order of increasing difficulty. Earlier problems are representative of a rigorous middle school curriculum. Later problems include basic concepts from high school mathematics. The hardest problems are designed to be challenging for all participants.
Nevertheless, all problems are solvable via clever or elementary methods. A familiarity with arithmetic and algebra is sufficient to solve a sizable portion of the problems.
The grading system is explained here.
For each individual round, only the top 3 scores will count towards the team score.
Earlier problems involve simple arithmetic, algebraic, and geometric concepts. Later problems require more insight.
The speed round is 25 questions (50 points total). Harder problems are worth more points than easier ones. This round is 30 minutes long.
The accuracy round is 11 problems (50 points total). Harder problems are worth more points than easier ones. The test is 40 minutes long.
The last question (#11) does not count for points in the accuracy round. It is an estimation question where students will try to estimate the answer to a question that is almost impossible to compute exactly. (Example: How many primes are there between 0 and 2014!). Ties in the accuracy round will be broken using the answer to this question.
The team round is quite different than team rounds in standard math competitions. The entire test will not be given at once; rather, problems will be handed out in sets of 3. Only when a previous set has been passed in will a team receive the next set.
At the signal, a designated “runner” is sent up to collect the first set of problems and bring them back to his/her team. Once the team has completed that set, the runner goes back up, drops off the answers, and returns with a new set.
There are a total of 7 sets of 3 problems followed by one estimation question at the end. The questions in the first set are 4 points, second set are 5 points, etc., and the problems in the seventh set are 10 points. Finally, in the eighth set, there is a single estimation problem worth 13 points. Partial credit is not given for any of the problems throughout the competition except for the problem in the last round. The problems increase in order of difficulty, starting with simple mathematical concepts, and increasing to mid-AIME level problems in the final sets. The entire round lasts 60 minutes and is worth 160 points.