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12th Annual Harvard-MIT Mathematics Tournament #0iwl

12th Annual Harvard-MIT Mathematics TournamentHard

From module Advanced Counting

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Understand the scale
Scale 0.5: Easiest math competition problems, often solvable even for early middle school students without experience. 1: Problems strictly for beginners, often at a moderate middle school level. 1.5: Problems for stronger beginner students, on the level of the middling problems in most middle school contests. 2: For motivated beginners, harder questions from the previous categories. 2.5: More advanced beginner problems, hardest questions from previous categories. 3: Early intermediate problems that require more creative thinking. 3.5: Tougher early intermediate problems that consistently stretch into higher-level creative thinking or conceptual knowledge. 4: Intermediate-level problems. 4.5: Upper intermediate problems approaching the upper bound for non-invitational sprint math competitions. 5: More difficult AIME problems or simple proof-based Olympiad-style problems. 6: High-level AIME-styled questions or introductory Olympiad-level questions. 7: Tougher Olympiad-level questions, may require more technical knowledge. 8: High-level Olympiad-level questions. 9: Expert Olympiad-level questions. 9.5: The hardest problems appearing on Olympiads which the strongest students could reasonably solve. 10: Historically notorious problems, generally unsuitable for even very hard competitions because they are exceedingly tedious, long, and difficult.
CirclesCartesian coordinatesCombinatorics

Problem

Problem:

Descartes's Blackjack: How many integer lattice points (points of the form (m,n)(m, n) for integers mm and nn) lie inside or on the boundary of the disk of radius 20092009 centered at the origin?

If your answer is higher than the correct answer, you will receive 00 points. If your answer is dd less than the correct answer, your score on this problem will be the larger of 00 and 25−⌊d/10⌋25 - \lfloor d / 10 \rfloor.

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