IMO Shortlist 1988 problem 20
Dodao/la: arhiva2. travnja 2012.
Find the least natural number
such that, if the set
is arbitrarily divided into two non-intersecting subsets, then one of the subsets contains 3 distinct numbers such that the product of two of them equals the third.
Izvor: Međunarodna matematička olimpijada, shortlist 1988