A googol is the large number 10100. In decimal notation, it is written as the digit 1 followed by one hundred zeroes:
Written out in ordinary decimal notation, it is 1 followed by 10100 zeroes; that is, a 1 followed by a googol of zeroes.
A googol is 10 to the 100th power, which is 1 followed by 100 zeros.
Google is the word that is more common to us now, and so it is sometimes mistakenly used as a noun to refer to the number 10100. That number is a googol, so named by Milton Sirotta, the nephew of the American mathematician Edward Kasner, who was working with large numbers like 10100.
This moniker is rather aspirational, as the number of atoms in the entire universe is estimated to be only 1080 , much less than a googol. A (big) step up from there is googolplex, which is 10googol , or 1 with a googol of zeros. This is the last widely accepted name for a really big number.
A googol, officially known as ten-duotrigintillion or ten thousand sexdecillion, is a 1 with one hundred zeros after it. Written out, a googol looks like this: 10,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000.
After a billion, of course, is trillion. Then comes quadrillion, quintrillion, sextillion, septillion, octillion, nonillion, and decillion.
There's not a googol of anything physical in the universe. On the other hand, numbers larger than a googol routinely arise in application. When you're counting potential things rather than physical things you can run into numbers much larger than a googol. This happens all the time in probability calculations.
Zillion is not actually a real number; it's simply a term used to refer to an undetermined but extremely large quantity.
noun, plural cen·til·lions, (as after a numeral) cen·til·lion. a cardinal number represented in the U.S. by 1 followed by 303 zeros, and in Great Britain by 1 followed by 600 zeros. amounting to one centillion in number.
But fair warning, Googolplex Written Out spans this many volumes: 10,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000. Each of those volumes holds a million zeros.
Googolplex may well designate the largest number named with a single word, but of course that doesn't make it the biggest number. In a last-ditch effort to hold onto the hope that there is indeed such a thing as the largest number… Child: Infinity! Nothing is larger than infinity!
Zillion sounds like an actual number because of its similarity to billion, million, and trillion, and it is modeled on these real numerical values. However, like its cousin jillion, zillion is an informal way to talk about a number that's enormous but indefinite.
Graham's number is bigger than the googolplex. It's so big, the Universe does not contain enough stuff on which to write its digits: it's literally too big to write.
In the American system each of the denominations above 1,000 millions (the American billion) is 1,000 times the preceding one (one trillion = 1,000 billions; one quadrillion = 1,000 trillions).
With this definition, there is nothing (meaning: no real numbers) larger than infinity.
A googolplex is a very large number that comes way after a trillion. It is so large that there is no known use in math. Some mathematicians and astronomers even have some theories that the number googolplex is greater than the total number of atoms in the universe.
The sequence of natural numbers never ends, and is infinite.
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.
How many zeros does 1 trillion have? One trillion is equivalent to 1000000 million or in words, we can say that one million million, that is, 1, 000, 000, 000, 000. Therefore, one trillion has 12 zeros.
A little bit of research shows that next on the list is quadrillion, followed by quintillion, sextillion, septillion, octillion, novillion, and decillion, which is 33 zeros.