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MathNet 2023-part-05 — 191 problems (EN–VI) Question 48

Math Olympiad Vault · MathNet 2023-part-05 — 191 problems (EN–VI)

Question 48

Let the numbers $r, s \in [1, \infty)$ with the property that for every positive integers $a, b$, with $a$ dividing $b$, it results that $[ar]$ divides $[bs]$.
a) Prove that $\frac{s}{r}$ is a positive integer.
b) Show that $r$ and $s$ are positive integers.
*Remark.* By $[x]$ we denote the floor of the real number $x$.