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

my $number_list = '950581.NumberList';
my $looking_for = '950581.LookingFor';

my %remember;
open my $NUMBER_LIST, '<', $number_list or die "$number_list: $!";
while (<$NUMBER_LIST>) {
    next if /Th|^$/;                  # Skip text and empty lines
    my ($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;
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