Wouldn't this be more versatile (chomp or no chomp)?

while(defined(my $line = <STDIN>)){
  print $1,"\n" if( $line =~ m/\W?(\d)\W?/ );
}
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Update As Enlil pointed out, {1} is implied by \d... I guess I more or less meant it to color the fact it was only one digit hungry.

YA update Ok, i will try to actually read before posting next time. As Cody Pendant pointed out, the intent seems to be only these characters, not CONTAINS these characters.