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

my $FALSE            = 0;
my $TRUE            = 1;
my $Flag            = $TRUE;
my $number_list = "TmpIPFile";
my $looking_for = "TmpLookingForIPFile";

my $DestDevice    = "Box";
my %remember;

if ($Flag == $TRUE){
   open my $NUMBER_LIST, '<', $number_list or die "$number_list: $!";
   while (<$NUMBER_LIST>) {
      next if /^sh|^\s*Source|^$DestDevice|^Accounting|^^M|^$|/;    # Skip text and empty lines
      my ($key, $value,) = split;
      push @{ $remember{$key} }, $value;
   }
   close $NUMBER_LIST;

   open my $LOOKING_FOR, '<', $looking_for or die "$looking_for: $!";
   while (<$LOOKING_FOR>) {
      chomp;
      for my $value (@{ $remember{$_} }) {
         print "$_ $value\n";
         # Do your calculations here...
      }
   }
   close $LOOKING_FOR;
}