open(MAIL, "|/usr/lib/sendmail timekeeper@superaccurateclock.com");
print MAIL <<END;
From: Number Printer <numprint\@printnum.com>
Subject: What Year is it?

Please enter the year below and reply.
Year:
END
close(MAIL);
# ok, now watch our mail spool for the answer

open(SPOOL, "tail -f /var/mail/spool/numprint |");
while(<SPOOL>) {
  if(/Year: (\d+)/) { $year = $1; last; }
}
close(SPOOL);

# now we know for sure what year it is, we can use any
# of the other suggestions to print the numbers