how can i calculate etimated P/E for a stock?

Question

if company x made $3 billion in the first half of 2006, issued shares = 6 billion shares, today's price is $12, what is the estimated P/E for full 2006 year.

Answer 1

So the company made .50 cents a share. Given that P/E=12/.5 = 24. the P/E ratio is calculating for the past earning as you don't know what future earning are you can't calcute forward P/E

Answer 2

To calculate estimaed P/E, you need to estimate next year's earnings per share and divide the current price by those earnings.