# Modular Arithmetic Readings

For this first reading, you will need to access several external webpages provided by Khan Academy. Once you have completed all of the readings and practices, click the**Next**button below to continue the reading for Unit 1.

- What is Modular Arithmetic?
- Practice—Using the Modulo Operator
- Congruence Modulo
- Congruence Relation Practice
- Equivalence Relations
- The Quotient Remainder Theorem
- Modular Addition and Subtraction
- Practice—Modular Addition