How Many Aliens are Out There?

Nobody knows how many aliens there are out there, and if any of them are looking for us. BUT... we can take a guess. A really good guess. That guess is called the Drake Equation, which will calculate how many alien civilizations there are just in our one galaxy. And you can use it right now to see how many ETs might be looking for you!
First, you need to know how many stars there are in our Milky Way Galaxy.
Scientists are pretty sure the Milky Way has between 200 billion and 400 billion stars (that's 400,000,000,000!) But there may be even more, or perhaps you want to know how many aliens there are in a smaller or bigger galaxy. Choose whatever number seems fun!
How Many Stars Are There in The Milky Way?