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Basic element of mathematics used for counting, measuring, solving equations, and comparing quantities. They fall into several categories. The counting numbers are the familiar 1, 2, 3 . . . ; whole numbers are the counting numbers and zero; integers are the whole numbers and the negative counting numbers; and the rational numbers are all possible quotients formed by integers, including fractions. These numbers can be symbolically represented by terminating or repeating decimals. Irrational numbers cannot be represented by fractions of integers or repeating decimals and must be represented by special symbols such as , e, and . Together, the rational and irrational numbers constitute the real numbers, which form an algebraic field (seefield theory), as do the complex numbers. While the counting numbers and rational numbers come about as the means of counting, calculating, and measuring, the others arose as means of solving equations. See alsotranscendental number.
This entry comes from Encyclopædia Britannica Concise. For the full entry on number, visit Britannica.com.