3-digit number of buses wanted
Source: Chile Finals 2008 L2 p1
October 5, 2022
number theoryDigits
Problem Statement
Alberto wants to invite Ximena to his house. Since Alberto knows that Ximena is amateur to mathematics, instead of pointing out exactly which Transantiago buses serve him, he tells him: the numbers of the buses that take me to my house have three digits, where the leftmost digit is not null, furthermore, these numbers are multiples of , and the second digit of them is the average of the other two.
What are the bus lines that go to Alberto's house?