Googol
A googol is the large number 10^100, that is, the digit 1 followed by one hundred zeros:
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
The term was coined in 1938 by 9-year-old Milton Sirotta (1929–1981), nephew of American mathematician Edward Kasner. Kasner popularized the concept in his book Mathematics and the Imagination (1940).
Other names for googol include ten duotrigintillion on the short scale, ten thousand sexdecillionon the long scale, or ten sexdecilliard on the Peletier long scale.
A googol has no particular significance in mathematics, but is useful when comparing with other very large quantities such as the number of subatomic particles in the visible universe or the number of possible chess games. Edward Kasner used it to illustrate the difference between an unimaginably large number and infinity, and in this role it is sometimes used in teaching mathematics.
Googolplex
A googolplex is the number 10googol, i.e. 10(10^100). In pure mathematics, the magnitude of a googolplex could be related to other forms of large number notation such as tetration, Knuth's up arrow notation, Steinhaus-Moser notation, or Conway changed arrow notation.
