use strict;
use warnings;

my %toWord = (
    "1" => "one",
    "2" => "two",
    "3" => "three",
    "4" => "four",
    "5" => "five",
    "6" => "six",
    "7" => "seven",
    "8" => "eight",
    "9" => "nine"
    );

print <<MSG;
This program will ask you to type in two numbers and then add those numbers together.
It will then display the problem and the answer in word form.
MSG

while (1) {
    my $user1 = getDigit(4, ' or type done to exit') or next;
    last if $user1 eq "done";

    my $user2 = getDigit(5) or next;
    my $sum = ($toWord{$user1 + $user2});

    $user1 = (ucfirst $toWord{$user1});
    print "$user1 plus $toWord{$user2} equals $sum\n";
}


sub getDigit {
    my ($last, $extra) = @_;

    $extra .= ': ';
    print "Enter and integer between one and $toWord{$last}$extra";
    chomp(my $value = <STDIN>);

    if ($value !~ /^([1-9]|done)$/) {
        print "I don't understand '$value'\n";
        return;
    }

    return $value if $value =~ /^done$/ || $value <= $last;

    print "$toWord{$value} is not in the range one to $toWord{$last}.\n";
    return;
}