"We don't do homework for you..." (Anonymous Monk)

This ain't true, as you can see - but it may be the provided solutions don't meet your specs sometimes ;-)

So i feel free to put in my 2 ˘:

Edit: In German this sounds much better: Ich bin so frei, meinen Senf dazu zu geben.

#!/usr/bin/env perl

use strict;
use warnings;
use List::Util qw(reduce);
use feature qw (say);

my $n = shift || die qq(Usage $0 [number]);

say reduce { $a + $b } 1 .. $n;

__END__
[download]

Please see also There's more than one way to do it as well as List::Util.

Best regards, Karl