One of the most common applications of advanced mathematics is in encryption. The RSA encryption algorithm is the most common version, and is the basis of the security that underlies the https protocols used to connect users to online retailers, banks, and so forth. This also concludes the first volume of the Math From Scratch, which can be obtained in a single document through Graphicly. Join us when we return in September with the goal of defining rational, irrational and real numbers.