Number Theory/Notation and Introduction to proof

Notation

$\N \,$ is the set of positive integers, also called the natural numbers.

$\Z \,$ is the set of all integers.

$\mathbb{Q} \,$ is the set of all rational numbers.

$\mathbb{A} \,$ is the set of algebraic numbers.

$\R \,$ is the set of real numbers.

$\C \,$ is the set of complex numbers.