How many $8$-digit numbers are $*2*0*1*7$, where four unknown numbers are replaced by stars, which are divisible by $7$?
Problem
Source: Czech-Polish-Slovak Junior Match 2017, Team p3 CPSJ
Tags: Digit, divisible, number theory
Source: Czech-Polish-Slovak Junior Match 2017, Team p3 CPSJ
Tags: Digit, divisible, number theory
How many $8$-digit numbers are $*2*0*1*7$, where four unknown numbers are replaced by stars, which are divisible by $7$?