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2023 OIM Problems/Problem 1

Revision as of 03:11, 14 December 2023 by Tomasdiaz (talk | contribs) (Created page with "== Problem == Let <math>n</math> be a positive integer. The following 35 multiplications are performed: <cmath>1 \cdot n,2 \cdot n,\cdots ,35 \cdot n</cmath> Show that in at...")
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Problem

Let $n$ be a positive integer. The following 35 multiplications are performed:

\[1 \cdot n,2 \cdot n,\cdots ,35 \cdot n\]

Show that in at least one of these results the digit 7 appears at least once.

Solution

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See also

https://sites.google.com/associacaodaobm.org/oim-brasil-2023/pruebas

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