#!/usr/bin/perl

use strict;
use warnings;

my @a=qw( 1 2 3 4 a b c g f);
    
my $s=0;

foreach my $i(@a){
	$s+= $i;
	print "i: $i - s: $s\n";
}
print $s;

##</code><code>##

D:\>perl derp.pl
i: 1 - s: 1
i: 2 - s: 3
i: 3 - s: 6
i: 4 - s: 10
Argument "a" isn't numeric in addition (+) at derp.pl line 10.
i: a - s: 10
Argument "b" isn't numeric in addition (+) at derp.pl line 10.
i: b - s: 10
Argument "c" isn't numeric in addition (+) at derp.pl line 10.
i: c - s: 10
Argument "g" isn't numeric in addition (+) at derp.pl line 10.
i: g - s: 10
Argument "f" isn't numeric in addition (+) at derp.pl line 10.
i: f - s: 10
10