Browse · MathNet
Print51st Ukrainian National Mathematical Olympiad, 3rd Round
Ukraine algebra
Problem
Olesya wrote down a natural number . After this, Andriy wrote down one sixth, one fifth, one fourth, one third and a half of . It turns out that the sum of all numbers that are written is integer. What is the least possible number that Olesya could write?
Solution
The sum is given by: , and therefore is divisible by and the result follows.
Final answer
20
Techniques
FractionsDivisibility / Factorization