There is a wide variety of Mathematics used at Google. For example Linear Algebra in the PageRank algorithm, used to rank web pages in search results. Or Game Theory, used in ad auctions, or Graph Theory in Google Maps. At Google there are literally dozens of products which use interesting Mathematics. These are not just research prototypes, but real Google products; in which Mathematics play a crucial role. In this presentation, I introduce several applications of Mathematics at Google. I begin with a detailed explanation of search on the web and PageRank. Then I show a dozen examples of Google products and the corresponding Mathematics that are used. The presentation has an extensive list of links and references. And it's available in English and Spanish.