$ cat diff.pl use strict; use warnings; my $n1 = '-933'; # the same result my $n2 = '-1039'; # without quotes my $diff = $n1 - $n2; print "diff: $diff\n"; $ perl diff.pl diff: 106 $ perl -V Summary of my perl5 (revision 5 version 8 subversion 8) configuration: Platform: osname=linux, osvers=2.6.9-22.18.bz155725.elsmp, archname=i386-linux-thread-multi uname='linux hs20-bc1-6.build.redhat.com 2.6.9-22.18.bz155725.elsmp #1 smp thu nov 17 15:34:08 est 2005 i686 i686 i386 gnulinux '