Youxing Z

Definition

We call a set numbers if the elements can be calculate under some closed rules.

Examples:

• Integer ($\mathbb Z$): $${0,1,2,3,...}$$

• Rational Number ($\mathbb Q$): $${0,\dfrac{1}{2},\dfrac{2}{3},...}$$

• Real Number ($\mathbb R$): $${0,1,\dfrac{1}{2},\pi,\sqrt 2,...}$$

• Complex Number ($\mathbb C$): $${0,i,\dfrac{1}{2},\pi,\sqrt 2 + 5i,...}$$