#!usr/bin/perl
use strict;
use warnings;

foreach my $ssn qw(123-45-6789 
                   987654321)
{
   my $digits = $ssn;
   $digits =~ s/-//g;
   print "$ssn   \t$digits\n";
}
__END__
prints:
123-45-6789     123456789
987654321       987654321