Fantastic numbers
Source: 2021 Iran second round mathematical Olympiad P2
May 15, 2021
number theoryDigits
Problem Statement
Call a positive integer "Fantastic" if none of its digits are zero and it is possible to remove one of its digits and reach to an integer which is a divisor of . ( for example , 25 is fantastic , as if we remove digit 2 , resulting number would be 5 which is divisor of 25 ) Prove that the number of Fantastic numbers is finite.