MathDB
Balls, bags and powers of three

Source: Argentina IberoAmerican TST 2024 P6

August 9, 2024
combinatoricsnumber theory

Problem Statement

Uri has 9999 empty bags and an unlimited number of balls. The weight of each ball is a number of the form 3n3^n where nn is an integer that can vary from ball to ball (negative integer exponents are allowed, such as 34=1813^{-4}=\dfrac{1}{81}, and the exponent 00, where 30=13^0=1). Uri chose a finite number of balls and distributed them into the bags so that all the bags had the same total weight and there were no balls left over. It is known that Uri chose at most kk balls of the same weight. Find the smallest possible value of kk.