When Facebook goes public this week, the company will be valued at roughly $100 billion.
It will be the highest valuation ever for an initial public offering of a tech company. Is Facebook really worth this much money?
One way to frame the question is to consider a single fraction.
The number on top of the fraction is the total value of the company. The number on the bottom is the company's profits over the past year. This fraction is called the price-to-earnings ratio. It's widely used by investors in stocks.