MathDB
blackboard numbers: a -> a:Ν mod N -> ... ->0 , sum of ... >100N

Source: Tournament of Towns, Junior A-Level Paper, Spring 2020 , p7

June 10, 2020
combinatoricsgameremainder

Problem Statement

Gleb picked positive integers NN and aa (a<Na < N). He wrote the number aa on a blackboard. Then each turn he did the following: he took the last number on the blackboard, divided the number NN by this last number with remainder and wrote the remainder onto the board. When he wrote the number 00 onto the board, he stopped. Could he pick NN and aa such that the sum of the numbers on the blackboard would become greater than 100N100N ?
Ivan Mitrofanov