Glacial flooding threatens millions globally

Fifteen million people around the world are at risk from flooding caused by glacial lakes, with just four countries accounting for more than half of those exposed.

Unifying colors by primes

Isaac Newton's theory of light indicates that all colors can be generated from three basic colors: red, green, and blue. RGB (Red, Green, Blue), a light-color structure that contains 3Ă—256 values of letter symbols, and CMYK ...

The first lab-created 'quantum abacus'

Do you want to know whether a very large integer is a prime number or not? Or if it is a "lucky number"? A new study by SISSA, carried out in collaboration with the University of Trieste and the University of Saint Andrews, ...

How non-native tree species affect biodiversity

Non-native forest tree species can reduce native species diversity if they are planted in uniform stands. In contrast, the effects of introduced species on soil properties are small. This was found by an international review ...

Sun releases strong solar flare

The sun emitted a strong solar flare, peaking at 1:50 p.m. EST on Jan. 9, 2023. NASA's Solar Dynamics Observatory, which watches the sun constantly, captured imagery of the event.

Strong solar flare erupts from Sun

The Sun emitted a strong solar flare, peaking at 7:57 p.m. EDT on Jan. 5, 2023. NASA's Solar Dynamics Observatory, which watches the Sun constantly, captured an image of the event.

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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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