In mathematics, a real number is almost any number you would use in real life. Real numbers include whole numbers (such as 1, 2, 3), rational decimal numbers (32.3), irrational numbers (π), and negative numbers (-4). They are called "real" to differentiate them from "imaginary" (or "complex") numbers, which include a component multiplied by i, the square root of -1. Some real numbers can be difficult to use in computers, which must represent long or nonterminating numbers in a finite number of bits. As a result, some real numbers may be approximated, or rounded, to create a finite, floating-point representation.