The book Geek Logik by Garth Sundem attempts to break down a number of every day decisions into mathematical equations. It's an interesting read, and as I like numbers, I thought I'd include his "Should I buy it" equation here. I take no credit for the actual equation, but hopefully this calculator will help you make a purchase desicion!

Should I buy it?

Here is what infomation we need to work out this equation: