#!/usr/bin/perl -w

use strict;

my $n = 100;
my $sum = 0;

$sum += $_ for 1 .. $n;

print "$sum\n";

##</code><code>##

Sum(1..n) = n(n+1)/2

##</code><code>##

#!/usr/bin/perl -w

use strict;

my $n = 100;
my $sum = $n * ( $n + 1 ) / 2;

print "$sum\n";