Graham's Number

Graham’s number makes Avogadro’s number (a casual 6.02214129 x 10^23, the number of hydrogen atoms in a single gram of hydrogen) look like child’s play.

Graham’s number is so big that it’s bigger than the total number of atoms in the observable universe. It’s so big there’s not enough room to write it here unless you understand really advanced math symbols (think: a number with a zillion exponents on top of exponents).

So what is it for? As you could probably tell, Graham’s number is a result of math and theory, rather than based in physical reality. Graham’s number is the upper bound to a math problem known as the Ramsey theory, making it the largest specific, positive integer ever used in a math proof before.

The Ramsey theory is a part of combinatorics: being able to find order in any system, as long as it’s big enough. But how big? Graham’s-number-big...which, again, is more than the atoms in the universe.