Berkeley Math Circle Monthly Contest 2 #0hoa

Berkeley Math Circle Monthly Contest 2Hard

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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.

FractionsPolynomial operations

Problem

Problem:

\frac{a}{b} \quad \text{ and } \quad \frac{c}{d}

are called approximately equal if $a, b, c, d$ are positive integers and

\frac{a}{b}-\frac{c}{d}=\frac{1}{b d}

Prove that given two approximately equal fractions, we can multiply the four numerators and denominators by the same positive integer and then add or subtract 1 from each of them so that the resulting fractions are equal.

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