Can you tell me the names of large numbers? Like what would 5,000,000,000 be? And how large are millions, billions, etc? Also millionths, billionths, etc?

Professor Homunculus' answer:

That is a very common question, and it seems that teachers need to spend more time and effort making sure that every students learns them well by elementary school.

First, let's clear up some terms:
It turns out that in different countries, they use different names. The British and the Americans (USA) ("two nations separated by a common language") use the -illions differently.

In American English, after each -illion come the ten -illions, and hundred -illions, then the next -illion.

In the British and some other European nations' systems, there are -illions, ten -illions, hundred -illions, then thousand illions (sometimes call -illiards, with the same prefix as the previous -illion).

If you are in the USA, you usually don't come across the other systems too much. They are even going out of style in the other countries due to being overwhelmed by American influences, scientific and otherwise. The British have officially adopted the American system. Is this good? Who knows? It does make it a bit simpler if you are an American, though not necessarily better.

Why are there two systems? I say "potato," you say "potahto." Each one does make it's own sense, (see if you can figure out what it is) neither is 100% better.

Here is a pretty large list: (In real life, you will probably never need to go beyond the millions, unless you are Bill Gates.)
The numbers which look like 6 x 10^9 are read "six times ten to the 9th power". That is what is called scientific notation. You can see how a large number can be more conveniently expressed in scientific notation that as a regular number or a word.

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• An interesting rule of thumb, is if you have an even prefix of the -illion (like quadrillion) in the American system, then it's British or European counterpart will be the half of the prefix (half of quad- is bi-) ending in -iard. So six sextillion would be six trilliard (or six thousand trillion) in the UK.
  
  
• If you have an odd prefix of the -illion (like quintillion) in the American system, then it's British or European counterpart will be the half of the prefix higher than the -illion (the prefix higher than quin- is sex-, and half of sex- is bi-) and end in -ion. So six quintillion in the U.S. would be six trillion in the UK.
  
  
• Interestingly enough, if the -illion prefix is even (bill -, quad-, sex-, oct-, etc.) the power of ten for the -illiard will be odd (and a multiple of 3, and 9 or higher).
  

There are names for larger numbers, but you will impress anyone you need to with the Latin nomenclature up until vigintillion. Other numbers have special names, often associated with a specific function.

The most famous "big number name" is the googol, which is 10 to the hundredth power, or 1 followed by 100 zeroes. It is also know as 10 dotrigintillion.

Want to know how much a googolplex is ? Drop me an e-mail and I might tell you!

What about zillions, gazillions, godzillians, and cotillians?

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What about the names of very small numbers? Here is a list:

A rule of thumb to help you remember the American names of small numbers:

With the large numbers, you know that 10 has one zero in it, 100 has two zeros, and so on. For the small numbers, the number that sounds like the large number has one less zero than the large number. For instance, ten has one zero in it. A tenth has no zeros in it. Another example is: A million has 6 zeros in it, so a millionth as only 5 zeros in it.

Here's a practical example: you see this number: 0.0004. There are three zeros between the 4 and the decimal point. Imagine one less zero, but behind the 4 instead of in front of it. You would call that number "four hundred." So the number that sounds like that is the name of our original number. Therefore, 0.0004 is called "four hundreths," (which sounds like four hundred.")

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