I need to find out the number of times a fair coin is needed to flipped, until head appears for the first time.

Now, the options are: 2, 8, 16, and 64.

I don't think it can be calculated. Because every time a coin is flipped, the chance of head appearing is .5 or 50%. 

How to calculate this?

Edit: I wrote the question according to the original question I found. The title was written accordingly. Seeing an experienced user's edit on my question, I guess the correct title is: 'The Average Number of Times a Coin Needs to Be Flipped Until Head Appears'.