Sounds like you just need to keep a count of how many guesses the user inputs. Increment the count each time you get do my $guess=<STDIN>; and it'll reflect the number of letters the user guessed.

#!/usr/bin/perl -w
#   hangman.pl
#  
use strict;
use warnings;

my @words=qw( portion answers printer program );
my @guesses=();
my $wrong=0;

my $choice=$words[rand @words];
my $hangman="0-|--<";

my @letters=split(//, $choice);
my @hangman=split(//, $hangman);
my @blankword=(0) x scalar(@hangman);

my $num_guesses = 0;

    while ($wrong < scalar(@hangman)) {
        foreach my $i (0..$#letters) {
                if ($blankword[$i]) {
                        print $blankword[$i];
                } else {
                        print "-";
                }
        }
        print "\n";
        if ($wrong) {
                print @hangman[0..$wrong-1];
        }
        print "\n Your Guess: ";
        my $guess=<STDIN>;
        chomp $guess;
        my $right=0;
        for (my $i=0; $i<@letters; $i++) {
                if ($letters[$i] eq $guess) {
                        $blankword[$i]=$guess;
                        $right=1;
                }
        }
        $wrong++ unless($right);
        $num_guesses++;
        if (join('', @blankword) eq $choice) {
                print "The word is '$choice'... You got it right in $n
+um_guesses guesses!\n";
                exit;
        }
    }
    
print "$hangman\nBetter luck next time, the word was '$choice'.\n";
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