Efthimiou takes out the calculator to prove that if a vampire sucked one person's blood each month -- turning each victim into an equally hungry vampire -- after a couple of years there would be no people left, just vampires. He started his calculations with just one vampire and 537 million humans on January 1, 1600 and shows that the human population would be down to zero by July 1602.
Take that Casper, Dracula and creepy friends.
