Israel 2011 Q5 - Process with two lists
Source: Israel National Olympiad 2011 Q5
August 8, 2019
combinatoricsnumber theoryProcesses
Problem Statement
We have two lists of numbers: One initially containing 1,6,11,...,96, and the other initially containing 4,9,14,...,99. In every turn, we erase two numbers from one of the lists, and write of their sum (not necessarily an integer) in the other list. We continue this process until there are no possible moves.[*] Prove that at the end of the process, there is exactly one number in each list.
[*] Prove that those two numbers are not equal.