
 Modular arithmetic  Wikipedia, the free encyclopedia 
  One way to understand modular arithmetic is to consider "24hour clock arithmetic": the arithmetic of timekeeping in which the day runs from midnight to midnight and is divided into 24 hours, numbered from 0 to 23. 
  In cryptography, modular arithmetic directly underpins public key systems such as RSA and DiffieHellman, as well as providing finite fields which underlie elliptic curves, and is used in and a variety of symmetric key algorithms including AES, IDEA, and RC4. 
  More generally, modular arithmetic also has application in disciplines such as law (see e.g., apportionment), economics, (see e.g., game theory) and other areas of the social sciences, where proportional division and allocation of resources plays a central part of the analysis. 
 en.wikipedia.org /wiki/Modular_arithmetic (1034 words) 
