Israel 2013 Q4 - Multiples of 7 made of digits 0,1,9
Source: Israel National Olympiad 2013 Q4
August 8, 2019
number theoryDigits
Problem Statement
Determine the number of positive integers satisfying:
[*]
[*] is divisible by 7
[*] does not contain any of the digits 2,3,4,5,6,7,8.