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MathNet 2016-part-02 — 184 problems (EN–VI) Question 111

Math Olympiad Vault · MathNet 2016-part-02 — 184 problems (EN–VI)

Question 111

Let $S_{n}$ be the sum of reciprocal values of non-zero digits of all positive integers up to (and including) $n$. For instance, $S_{13} = \frac{1}{1} + \frac{1}{2} + \frac{1}{3} + \frac{1}{4} + \frac{1}{5} + \frac{1}{6} + \frac{1}{7} + \frac{1}{8} + \frac{1}{9} + \frac{1}{1} + \frac{1}{1} + \frac{1}{1} + \frac{1}{1} + \frac{1}{2} + \frac{1}{1} + \frac{1}{3}$.
Find the least positive integer $k$ making the number $k! \cdot S_{2016}$ an integer.