MathDB
Version of ISL 2014 C2

Source: Austria MO Final round 2023 P4

May 27, 2023
algebra

Problem Statement

The number 20232023 is written 20232023 times on a blackboard. On one move, you can choose two numbers x,yx, y on the blackboard, delete them and write x+y4\frac{x+y} {4} instead. Prove that when one number remains, it is greater than 11.