【How-to】What is the longest number

A googol is the large number 10¹⁰⁰. In decimal notation, it is written as the digit 1 followed by one hundred zeroes: 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.