timethese( -3, {
  mod  => sub { $x % 10           },
  chop => sub { chop(my $x = $x) },
  substr => sub { substr($x, -1) },
});
__END__
(they ran for at least 3 seconds)

  chop:  8707.14/s  (n= 29256)
substr:  43620.45/s (n=136532)
   mod:  48906.87/s (n=163838)