Portal:Mathematics/Selected article/22

From Wikipedia, the free encyclopedia

< Previous Next >

edit  

Selected article 22

\mathbb{N} \sub \mathbb{Z} \sub \mathbb{Q} \sub \mathbb{R} \sub \mathbb{C}.
The natural numbers are part of the integers, which are part of the rationals, which are part of the reals, which are part of the complex numbers.
A number is an abstract entity that represents a count or measurement. A symbol for a number is called a numeral. The arithmetical operations of numbers, such as addition, subtraction, multiplication and division, are generalized in the branch of mathematics called abstract algebra, the study of abstract number systems such as groups, rings and fields.

Numbers can be classified into sets called number systems. The most familiar numbers are the natural numbers, which to some mean the non-negative integers and to others mean the positive integers. In everyday parlance the non-negative integers are commonly referred to as whole numbers, the positive integers as counting numbers, symbolised by \mathbb{N}..

The integers consist of the natural numbers (positive whole numbers and zero) combined with the negative whole numbers, which are symolised by \mathbb{Z} (from the German Zahl, meaning "number").

A rational number is a number that can be expressed as a fraction with an integer numerator and a non-zero natural number denominator. Fractions can be positive, negative, or zero. The set of all fractions includes the integers, since every integer can be written as a fraction with denominator 1. The symbol for the rational numbers is a bold face \mathbb{Q} (for quotient).

...Archive Read more...