earning per share calculation confusion for me


Who I calculate the eaning per share

I would suggest you read IAS 33 Earnings per share. There are a number of examples that will surely help you.

There are so many factors to be considered in the study of EPS that this forum is not the right place for a lengthy and arduous discussion.

Unless of course you're in a first-year class that isn't going to involve all that complicated stuff, in which case it's:

\text{\frac{net\ income\ -\ preferred\ dividends}{shares\ of\ outstanding\ common\ stock}}

If you don't recall how to determine preferred dividends, it's likely somewhere else in the same chapter or perhaps the chapter before. If you don't have any preferred dividends, don't let that confuse you -- that just means that number is zero.