I would recommend doing the following to help in troubleshooting:

#!/usr/bin/perl

use strict;    #  make sure these are on, you will have to declare all
+ your variables now
use warnings;  #

use 5.006;
use CGI::Carp qw( fatalsToBrowser warningsToBrowser );  # this will le
+t you see your script problems


$| = 1;  # continuously flush the print buffer

print "Content-type: text/html\n\n";   # move this to the top so your 
+web browser will display error messages

&form_parse;
$firstnumber = $FORM{'firstnumber'};
$secondnumber = $FORM{'secondnumber'};
$operation = $FORM{'operation'};


&printconfirmation;
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