A real number is a number that can be positive or negative and have decimal places after the point. Positive or negative, large or small, whole numbers or decimal numbers are on the whole Real Numbers. They are called "Real Numbers" since they are not Imaginary Numbers. The collection of all rational numbers and irrational numbers together is called real numbers, which is denoted by R. Real numbers are for the most part, grouped into rational and irrational numbers. Simplify the complex fundamentals of a subject topic like properties of real numbers, divisibility of integers, irrational numbers, etc.