IMO Shortlist 1999 problem N6


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2. travnja 2012.
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Prove that for every real number M there exists an infinite arithmetic progression such that:

- each term is a positive integer and the common difference is not divisible by 10
- the sum of the digits of each term (in decimal representation) exceeds M.
Izvor: Međunarodna matematička olimpijada, shortlist 1999