my $seed = "$name$email$item";
while ($seed =~/(.)/g) {
  $n += 1;
  if (uc($1) eq uc('a')) { $i = ($i + 173); }
  # many many lines and calulations here
}
my $m=sprintf("%.f",$i) ;
my $trimmedNumber = substr($m, -16, 16); # trim 16 from the right.
printf ("Trimmed: $trimmedNumber\n");