MathDB
Problem 3 -- Topsy Turvy Bases

Source: 46th Austrian Mathematical Olympiad National Competition Part 2 Problem 3

July 14, 2018
Austrianumber theorynumber base

Problem Statement

We consider the following operation applied to a positive integer: The integer is represented in an arbitrary base b2b \ge 2, in which it has exactly two digits and in which both digits are different from 00. Then the two digits are swapped and the result in base bb is the new number.
Is it possible to transform every number >10> 10 to a number 10\le 10 with a series of such operations?
(Theresia Eisenkölbl)