use strict;
use warnings;

for my $str ('1 2 3', 'a b c', ' a3 b2 c1') {
    next if $str !~ /\w?([0-9])/;
    my $mpos = $-[0];
    my $cpos = $-[1];
    
    print "Found $1 in '$str' at index $cpos. Overall match started at $mpos\n";
}

##</code><code>##

Found 1 in '1 2 3' at index 0. Overall match started at 0
Found 3 in ' a3 b2 c1' at index 2. Overall match started at 1