Join the kids of the Cryptoclub as they apply basic mathematics to make and break secret codes. The encryption systems covered in this book range from classic ciphers that have been around for hundreds of years, such as the Caesar and Vigenère ciphers, to the modern RSA system that provides security for information passed over the Internet. Connections are made to historical events and applications of recent mathematical research, giving students the opportunity to see mathematics as an exciting, changing subject.Mathematics topics covered include positive and negative numbers, decimals and percents, data analysis and probability, prime numbers and factorization, modular arithmetic, inverses, and exponentiation.