A googol is the number written as 1 followed by 100
10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000. Using exponential notation, this can be written as 10100.
A googol is such an incredibly large number that it defies the imagination. For example, a googol is much greater than the number of particles in the universe! The name "googol" was suggested in the 1930's by Milton Sirotta, the nine-year-old nephew of mathematician Dr. Edward Kasner, who also suggested the name "googolplex" for the number 10googol, which, if written out in full, would be 1 followed by a googol of zeroes. More names for big numbers.