Elementary number theory is a branch of mathematics that studies the properties of integers. It takes arithmetic as its main research method, and its main contents include integer divisibility theory, congruence theory, continued fraction theory and some special indefinite equations.

In elementary number theory, we need to master the following basic knowledge:

-Definition of Integer

-Concepts of separability, inseparability, factor, multiple, quotient, obvious factor, true factor, composite number, prime number, small factor, remainder, etc.

-Euclid algorithm and extended Euclid algorithm.