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:
“If I could live as a tree, as a river, as the moon, as the sun, as a star, as the earth, as a rock, I would. ...Writing permits me to experience life as any number of strange creations.”
—Alice Walker (b. 1944)
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—Benjamin Disraeli (1804–1881)
“The growing good of the world is partly dependent on unhistoric acts; and that things are not so ill with you and me as they might have been, is half owing to the number who lived faithfully a hidden life, and rest in unvisited tombs.”
—George Eliot [Mary Ann (or Marian)