#!usr/bin/perl -w

use strict;

my($old, $new, $total) = (1, 1, undef);

open DATA, ">>data.txt"
    or die "Couldn't access data.txt: $!";
sub math
{
    $total = $old + $new;
        print "$old + $new = $total\n";
        print DATA "$old + $new = $total\n";
    $old = $new;
    $new = $total;
    sleep(1);
}

while(1 eq 1)
{
    &math;
}