Dangerous numbers
Source: Russian TST 2021, Day 6 P3
March 21, 2023
number theorynumber base
Problem Statement
Given an integer , we call the number dangerous if divides the number , which is obtained by writing the digits of in base in reverse order, with . Prove that if there exists a three-digit (in base ) dangerous number for a given , then there exists a two-digit (in base ) dangerous number.