The conspicuous absence of women in India's labour force

India's rapid economic growth has been accompanied by falling fertility rates and higher educational attainment among women. These advances often lead to an increase in women entering the labour force, but there has been ...

Exobiology in a box

The International Space Station is the platform to study a variety of fields without gravity getting in the way. A new experiment is furthering the Station's capabilities for investigating exobiology, or the study of life ...

Declining insects? Bring back set-aside

What if there were no more insects? Recent media headlines all over the world have raised this question, often using apocalyptic terms. Remarkably, on 20 March 2019, the U.K. Parliament even took a few minutes off discussing ...

page 1 from 2


A number is a mathematical object used to count 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.

This text uses material from Wikipedia, licensed under CC BY-SA