9
Billion
discussing the count of a large number of objects, such as stars in the Observable Universe, the focus is not on calculating their literal quantity down to the last star. In such cases, understanding the order of magnitude is sufficient. It is considered that the number of stars in the Observable Universe is a figure with 22 digits, which is more conveniently represented as one followed by 21 zeros and written as 10 to the power of 21.
Moreover, this is a lower estimate. This means that there could be
as few as
or as many as
1 000 000 000 000 000 000 000,
9 999 999 999 999 999 999 999
Counting to a billion is practically possible only in theory. If you were to start counting one number per second right from the moment of your birth, without sleeping, eating, or taking breaks, you would reach a billion by the time you're 32 years old.
8 billion is the current population of the planet. Counting them all sequentially throughout a human lifetime is absolutely impossible; you would need to live for more than two hundred years to achieve that.
Approximately 100 billion people have lived on the planet throughout its history. That's about the same number of stars (slightly more) in our Milky Way galaxy, as well as the number of neurons in the human brain.
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