Mathematically, real numbers are intuitively defined as numbers corresponding to points on the number axis. Originally, real numbers were just numbers, but later the concept of imaginary numbers was introduced. The original numbers were called "real numbers"-meaning "real numbers".
Real numbers can be divided into rational numbers and irrational numbers, or algebraic numbers and transcendental numbers, or positive numbers, negative numbers and zero. A set of real numbers is usually represented by the letter r or r n, and r n represents an n-dimensional real number space. Real numbers are uncountable. Real number is the core research object of real analysis.
Real numbers can be used to measure continuous quantities. Theoretically, any real number can be expressed as an infinite decimal, and to the right of the decimal point is an infinite series (cyclic or acyclic). In practice, real numbers are often approximate to a finite decimal (n digits are reserved after the decimal point, and n is a positive integer). In the computer field, because computers can only store a limited number of decimal places, real numbers are often represented by floating-point numbers.