Team accomplishes precise measurements of the heaviest atoms

An international research team has successfully conducted ultra-precise X-ray spectroscopic measurements of helium-like uranium. The team, which includes researchers from Friedrich Schiller University Jena and the Helmholtz ...

EU looks to downgrade wolf protection status

The European Commission said Wednesday it wants to change the protection status of wolves—allowing them to be hunted—based on new data suggesting the animals pose a rising threat to livestock.

How early farmers in Scandinavia overcame climate change

As the world faces the challenges of present-day climate change, scientific inquiry is, among other objectives, exploring how human societies navigate environmental variations at large. Investigating the past provides valuable ...

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Number

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.

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