What does 9,600,000,000,000,000,000,000 mean?

Date: 11/20/96 at 09:47:15
From: Anonymous
Subject: Imagining large numbers

Dear Dr. Math,
	
My class is trying to find out what this number means:

9,600,000,000,000,000,000,000

Thank you.

Date: 12/11/96 at 21:55:06
From: Doctor Daniel
Subject: Re: Imagining large numbers

Hi there,

That's a really big number!

First, we'll give it a name...

            We call 1,000,000 a million,
                1,000,000,000 a billion, 
            1,000,000,000,000 a trillion, 
        1,000,000,000,000,000 a quadrillion, 
    1,000,000,000,000,000,000 a quintillion, and 
1,000,000,000,000,000,000,000 a sextillion.

Your number is 9,600,000,000,000,000,000,000, so it's 9 sextillion, 
600 quintillion. But that's not very helpful; I mean, what's a
sextillion?  To make things easier for me to write, let's say 
it's 10 sextillion. Close enough, right?

Let's think in terms of things your class can maybe imagine. Right 
now, there are about 5 billion (5,000,000,000) people on earth. If we 
divided 10 sextillion by 5 billion, we'd have 2 trillion as the 
quotient. So suppose there were something we all had 2 trillion of.  
Then all people together would have roughly 10 sextillion of them.  

But what do we all have roughly 2 trillion of? It'd have to be really
small, right? It turns out that we all have about that many nerve 
cells in our brains. So your really big number is something pretty 
close to the total number of nerve cells in people on Earth.  Wow!

That might give you a decent idea of how to imagine lots of big 
numbers; you can divide by the 5 billion people on Earth or the 
250,000,000 (250 million) people in the U.S.A. to get an idea of 
"every person's share."  Then try to find something that we all have 
that share of...

Here's another big number, to give another example: How much is
8,200,000,000,000?  The word for that is 8 trillion, 200 billion.  
But if we divide by the number of people in the US, that's roughly 
36,000.  That's not too bad a guess for, say, how much money the 
average person makes in a year in the US (actually, it's a little 
high).  So 8.2 trillion is then roughly the total amount of money from 
everyone in America's annual paycheck.  

Get the idea?  This trick works for a lot of "big, but not too big" 
numbers. 

If you want to learn more about large numbers, look in our archives 
at:

  http://mathforum.org/dr.math/faq/faq.large.numbers.html   

and

  http://mathforum.org/dr.math/tocs/large.elem.html   

-Doctor Daniel,  The Math Forum
 Check out our web site!  http://mathforum.org/dr.math/