MathDB
2012 ToT Spring Senior A p7 a pile of 100 pebbles

Source:

March 5, 2020
combinatorics

Problem Statement

Konstantin has a pile of 100100 pebbles. In each move, he chooses a pile and splits it into two smaller ones until he gets 100100 piles each with a single pebble. (a) Prove that at some point, there are 3030 piles containing a total of exactly 6060 pebbles. (b) Prove that at some point, there are 2020 piles containing a total of exactly 6060 pebbles. (c) Prove that Konstantin may proceed in such a way that at no point, there are 1919 piles containing a total of exactly 6060 pebbles.