A number is a mathematical object used to count, label, and measure. In mathematics, the definition of number has been extended over the years to include such numbers as zero, negative numbers, rational numbers, irrational numbers, and complex numbers.
Mathematical operations are certain procedures that take one or more numbers as input and produce a number as output. Unary operations take a single input number and produce a single output number. For example, the successor operation adds one to an integer, thus the successor of 4 is 5. Binary operations take two input numbers and produce a single output number. Examples of binary operations include addition, subtraction, multiplication, division, and exponentiation. The study of numerical operations is called arithmetic.
A notational symbol that represents a number is called a numeral. In addition to their use in counting and measuring, numerals are often used for labels (telephone numbers), for ordering (serial numbers), and for codes (e.g., ISBNs).
In common use, the word number can mean the abstract object, the symbol, or the word for the number.
Read more about Number: Classification of Numbers, Numerals
Famous quotes containing the word number:
“In this world, which is so plainly the antechamber of another, there are no happy men. The true division of humanity is between those who live in light and those who live in darkness. Our aim must be to diminish the number of the latter and increase the number of the former. That is why we demand education and knowledge.”
—Victor Hugo (1802–1885)
“In the U.S. for instance, the value of a homemaker’s productive work has been imputed mostly when she was maimed or killed and insurance companies and/or the courts had to calculate the amount to pay her family in damages. Even at that, the rates were mostly pink collar and the big number was attributed to the husband’s pain and suffering.”
—Gloria Steinem (20th century)
“The rising power of the United States in world affairs ... requires, not a more compliant press, but a relentless barrage of facts and criticism.... Our job in this age, as I see it, is not to serve as cheerleaders for our side in the present world struggle but to help the largest possible number of people to see the realities of the changing and convulsive world in which American policy must operate.”
—James Reston (b. 1909)