use strict;
use warnings;

sub bad_average {
   my $acc = 0;
   $acc += $_ for @_;
   return $acc / @_;
}

sub better_average {
   my $acc = 0;
   $acc += $_/@_ for @_;
   return $acc;
}

my @inputs = (1) x 65537; # 2**16 + 1
my $true_average = 1;

for my $adj (qw[bad better]) {
    my $func = "${adj}_average";
    no strict 'refs';
    my $average = &$func( @inputs );
    my $diff = $average - $true_average;
    print 
        "Error using $func is ", 
        $diff? "a nonzero number near $diff" : 0,
        "\n"
}

##</code><code>##

Error using bad_average is 0
Error using better_average is a nonzero number near 3.33066907387547e-015