I've got it. We all know owning Apple products make you cool, right? So:

coolness = (amount of Apple products in house * avg. of last two digits of their release dates) / 10

Or in short form:

C=AR/10

Problem solved. This equation is perfect. It's arranged so that owning a Newton is around 10 times cooler than owning an iPad, and 100 times cooler than owning a 1st gen iPod. Genius!

My coolness is 5, btw. What's yours?

Rav