What Is Expedential Growth?

We need one point two billion earths with the same current population that we have on this earth to reach that nine quintilian number. We are more than half way to reaching a human population that size in our doublings than going back to having one person. If we start with just one single drop of water place on the home plate, and we double that every minute, how long do you think it would take before the entire stadium would be filled with water? You know, that example is completely mine blowing.