A googol is the number 10 100 (10 raised to the 100th power or 1 followed by 100 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). A googol is much larger than the number of atoms in the Universe.
A googol is the large number 10100, that is, the digit 1 followed by one hundred zeros (in decimal representation). One way of grasping its size is to multiply 1,000,000 by itself 16 times, then multiply the result by ten thousand. The ultimate product of this operation is one googol: 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.