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All-Russian Olympiad Regional Round
2005 All-Russian Olympiad Regional Round
9.2
9.2
Part of
2005 All-Russian Olympiad Regional Round
Problems
(1)
19 cards and divisibility by 11
Source: All-Russian MO Round 4, 2005
4/2/2005
9.2 Given 19 cards. Is it possible to write a nonzero digit on each card in such a way that you can compose from these cards an unique 19-digits number, which is divisible by 11? (R. Zhenodarov, I. Bogdanov)
combinatorics proposed
combinatorics