# Real Numbers

Real numbers include all rational and irrational numbers. Thus real numbers are integers, fractions and decimals. They even include all positive and negative numbers.

The real number system consists of whole numbers, integers, natural numbers, rational numbers and irrational numbers.

Natural numbers: 1, 2, 3,…

Whole numbers: 0, 1, 2, 3, …

Integers: -1, 0, 1, 2, 3, …

Rational numbers: $\frac{-1}{4}$, -0.5, 2, 41

Irrational numbers : $\sqrt{2}$ , $\pi$, sin 60

Non real numbers: When we consider a number $\sqrt{-25}$ , we may not write it this as 5 or -5 since 5^{2} = 25 and (-5)^{2} = 25 and therefore $\sqrt{-25}$ is not a real number and that’s the reason $\sqrt{-25}$ is a non real or imaginary number.