Real Number System

A real number is any number that can be found on the number line, including both rational and irrational numbers.

Natural numbers are the set of positive integers starting from 1 (1, 2, 3, ...).

Whole numbers are the set of natural numbers including zero (0, 1, 2, 3, ...).

Integers are whole numbers that can be positive, negative, or zero (..., -3, -2, -1, 0, 1, 2, 3, ...).

Rational numbers are numbers that can be expressed as a fraction $$\frac{a}{b}$$ where $$a$$ and $$b$$ are integers and $$b \neq 0$$ .

Irrational numbers are numbers that cannot be expressed as a simple fraction, and their decimal representation is non-repeating and non-terminating (e.g., $$\pi$$ , $$\sqrt{2}$$ ).

$$\sqrt{9} = 3$$ , which is a natural, whole, integer, rational, and real number.

$$\frac{10}{2} = 5$$ , which is a natural, whole, integer, rational, and real number.

$$-\sqrt{16} = -4$$ , which is an integer, rational, and real number.

No, $$\pi$$ is an irrational number.