What is a googolplex?
A googolplex is 1 followed by a googol of zeros, or 10 to the power of a googol. It is so large that it could never be written out in full.
A googol is 1 followed by 100 zeros. A googolplex is 10 raised to that power, so it has a googol zeros. The name was suggested by Milton Sirotta, the young nephew of mathematician Edward Kasner, who wrote about it in 1940.
Writing a googolplex in full is impossible. There are only around 10 to the power of 80 atoms in the observable universe, far fewer than a googol, so there would not be enough atoms to write all the zeros, even if each zero were the size of an atom.
Is there anything bigger?
Yes. Mathematicians work with numbers far larger than a googolplex, such as Graham's number, which arose in a problem in combinatorics. And there is no largest number at all, because you can always add one.
Did You Know?
Google's headquarters in California is called the Googleplex, a playful reference to this number.