http://www.nytimes.com/2008/09/16/science/16angi.html?partner=rssnyt&emc=rss

Wow, it all makes sense now!

“You are shopping in a busy supermarket and you’re ready to pay up and go home. You perform a quick visual sweep of the checkout options and immediately start ramming your cart through traffic toward an appealingly unpeopled line halfway across the store. As you wait in line and start reading nutrition labels, you can’t help but calculate that the 529 calories contained in a single slice of your Key lime cheesecake amounts to one-fourth of your recommended daily caloric allowance and will take you 90 minutes on the elliptical to burn off and you’d better just stick the thing behind this stack of Soap Opera Digests and hope a clerk finds it before it melts.

One shopping spree, two distinct number systems in play. Whenever we choose a shorter grocery line over a longer one, or a bustling restaurant over an unpopular one, we rally our approximate number system, an ancient and intuitive sense that we are born with and that we share with many other animals.”