A googol is the large number 10¹⁰⁰, that is, the digit 1 followed by one hundred zeroes. The term was coined in 1938 by nine-year-old Milton Sirotta, nephew of American mathematician Edward Kasner. Kasner announced the concept in his book Mathematics and the Imagination. The Internet search engine, Google, was named as a pun on this number.

A googol is "approximately" equal to the factorial of 70, and its only prime factors are 2 and 5. In binary it would take up 333 bits.

The googol is of no particular significance in mathematics, nor does it have any practical uses. Kasner created it to illustrate the difference between an unimaginably large number and infinity, and in this role it is sometimes used in mathematics teaching.

Writing out a googol

A googol can be written in conventional notation, as follows:

1 googol = 10¹⁰⁰ = 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

Relation to -illion number names

Using the short scale, a Googol is equal to ten duotrigintillion.

Trivia

Googol was the answer to the million-pound question on Who Wants to Be a Millionaire when Major Charles Ingram attempted to defraud the quiz show on 10 September 2001.

If we drew a regular polygon with a googol sides that was 10²⁷ times the size of the known universe, it would still appear circular, even on the scale of a planck length.

A googol is greater than the number of particles in the known universe, which has been variously estimated from 10⁷² up to 10⁸⁷.

A googolplex is 1 followed by a googol of zeroes, or ten raised to the power of a googol: 10^googol = .

Since a googol plus 1 is the number of digits in a googolplex, it would therefore not be possible to write down or store the digits of a googolplex in decimal notation, even if all the matter in the known universe were converted into paper and ink or disk drives.

See also

• Large number
• Names of large numbers

References

• Kasner, Edward & Newman, James Roy Mathematics and the Imagination (London: Penguin, 1940; New York: Simon and Schuster, 1967; Dover Pubns, April 2001, ISBN 0486417034).
• 'Searching for the birth of the googol'