I've read this article multiple times since it first appeared and have shared it with everyone I know. It's informative and entertaining. I will say, however, that in recent years I found my math wasn't adding up, and I realized it's because the formula outlined in this article omits a key piece of information: whether the birds in question are living in a chicken coop or some other type of coop. Chickens kept in a chicken coop are inarguably chickens, but chickens kept in a duck coop, for instance, are obviously chicken-shaped ducks and not chickens, and so should not count against your chicken total. Just thought I'd leave this comment here in case anyone else's math isn't adding up even after reading this article. Otherwise, great article!