buzzthebuzzsaw was first to the finish line, here's a similar example:

use strict;
use warnings;

my %hash = ();
$hash{ chr($_) } = $_ - ord(q{A}) + 1 for (ord(q{A}) .. ord(q{Z}));
while (<DATA>) {
  chomp;
  my ($line, $sum) = ($_, 0);
  my @arr = split(//, $line);
  while (@arr) {
    my $char = shift(@arr);
    $sum += ($char =~ m/[A-Z]/) ? $hash{$char} : $char;
  }
  print qq{$line : $sum};
}

__DATA__
AD3
FG3
ZZ5
BR7
GT3
[download]

$ perl  -l 636032.pl
AD3 : 8
FG3 : 16
ZZ5 : 57
BR7 : 27
GT3 : 30
[download]