$ perl -MO=Deparse 443218.pl
my(@l) = ('10', '20', '30');
foreach $_ (@l) {
    my $t += $_;
}
print $t;
443218.pl syntax OK

##</code><code>##

$ cat 443218.pl
use warnings;
use strict;

my @l = qw/10 20 30/;
my $t += $_ foreach @l;
#my $t;
#$t += $_ foreach @l;
print $t;