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How Much is a
BILLION?
Astronomers estimate that there are more than 100 BILLION stars in our Milky Way Galaxy. That’s a lot of stars!
A “billion” is a very large number. Exactly how much is a billion? To help you visualize this number, you can use your power of estimation. It’s simple: start with a small amount and work your way out.
Let’s try it with oranges. Imagine…
10 oranges
would fill a large salad bowl
1 thousand oranges
would fill a pick up truck
1 million oranges
would fill a swimming pool
1 billion oranges
would fill a stadium to the brim!
Try it! It’s your turn to use your power of estimation.
For each of the five questions, first imagine what a small amount looks like and then imagine more and more. Do you think the total number is MORE or LESS than a billion?
How many hairs are on your head?
more than a billion
less than a billion
How to Write Big Numbers
Writing big numbers can take a lot of space.
If you write a 1 followed by three zeros,
you get 1,000 = one thousand
If you write a 1 followed by six zeros,
you get 1,000,000 = one million
If you write a 1 followed by nine zeros,
you get 1,000,000,000 = one billion!
That’s a lot of zeros! Astronomers often deal with even larger numbers such as a trillion (12 zeros) and a quadrillion (15 zeros). When astronomers write these really, really big numbers, they use a shorthand called scientific notation. For example, instead of writing out a billion using nine zeros (like this: 1,000,000,000), they write it like this: 109. The little number 9 means there are nine zeros.
Try it! It's your turn to use scientific notation.
How would you write a trillion (1,000,000,000,000)?
1010
1012
1016
Image Credits:
All illustrations by Jim Steck