sub passes {
    my $test_number = shift() || die "no test number";
    return 0 if ($test_number =~ /0/);        # no zero
    return 0 if ($test_number =~ /(.).*\1/);  # no dups
    for ( split(//,$test_number) ) {
        return 0 unless $test_number % $_ == 0 ;
    }
    return 1;
}