You're looking at the trailing P/E, which looks at the past four quarters of earnings, but for fast growing companies investors tend to use the forward P/E, whi

You're looking at the trailing P/E, which looks at the past four quarters of earnings, but for fast growing companies investors tend to use the forward P/E, which is based on estimates of the next four quarters. FB's forward P/E is 29, google's is 14. Neither estimate is perfect, but the forward P/E tends to take expected growth into account much more effectively.