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MathNet 2012 Question 52

Math Olympiad Vault · MathNet 2012

Question 52

For each positive integer $n$, let $s(n)$ be the sum of the digits of $n$. Find the smallest positive integer $k$ such that
$$
s(k) = s(2k) = s(3k) = \dots = s(2011k) = s(2012k).
$$