How many stars are there in Milky Way?

Who many stars are there in the Milky Way? NASA website has published a post that tries to answer to this question. But apparently, answer to this question is not simply as the counting the stars in the sky. There is no way to count by to by the stars in a galaxy. So we must go forward with speculation. But how can guess the number of stars in the galaxy? Here we first have to calculate the mass of galaxy and then determine how much of this mass is for stars. After we should see who much is the average mass of a star. But even we don't know how much is an ordinary star in Milky Way? Does the sun of solar system is an average star? How do we know? This is why estimate of stars number is not comfortable or even accurate. Suppose you have a ten kilogram bag. If you open the bag, you will see number of coins in, with some rice and chocolate, chickpeas and other beans and pieces. However, you see these in the head of bag and under the bag may be there are other things that you never know what they are. Now think you want to guess the number of coins in the bag. So this is a difficult task. Because you can only count the number of coins that you can see. On the other hand, you have no idea that the coins scattered in all this bag is the same part that you can see with your eyes or not. But let's imagine your guess is that ten percent of the bag's weight is coins. But the size and weight of 50 cents with 100 cents coins is different. You should consider the average weight. Now extend this bag to the Milky Way. You will realize that it's not easy to count the stars in this galaxy. However, astronomers guess something. They say the numbers of stars in our galaxy are at least 100 billion and in the highest condition are 400 billion stars. However, even there are estimates more than this. Yes! The Milky Way is really great.