IMO Shortlist 2004 problem N5
Dodao/la:
arhiva2. travnja 2012. We call a positive integer alternating if every two consecutive digits in its decimal representation are of different parity.
Find all positive integers
such that
has a multiple which is alternating.
%V0
We call a positive integer alternating if every two consecutive digits in its decimal representation are of different parity.
Find all positive integers $n$ such that $n$ has a multiple which is alternating.
Izvor: Međunarodna matematička olimpijada, shortlist 2004
Školjka 
