Tiny particles lead to brighter clouds in the tropics

When clouds loft tropical air masses higher in the atmosphere, that air can carry up gases that form into tiny particles, starting a process that may end up brightening lower-level clouds, according to a CIRES-led study published ...

New large-sized insect species discovered in tropical forest

Scientists at the Biodiversity Unit of the University of Turku in Finland have studied the diversity of tropical parasitoid wasps for years. Parasitoid wasps are among the most species rich animal taxa on Earth, but their ...

Madrid to clip wings of noisy parakeets

Faced with a soaring population of noisy parakeets affecting the environment city authorities in Madrid said Monday they have decided to take steps to cut their numbers.

Daddy daycare: Why some songbirds care for the wrong kids

Interspecific feeding—when an adult of one species feeds the young of another—is rare among songbirds, and scientists could only speculate on why it occurs, but now, Penn State researchers have new insight into this behavior.

Bacteria make pearl chains

For the first time, scientists in Bremen were able to observe bacteria forming pearl chains that protrude from the cell surface. These pearl chains serve to better absorb and store substances from the environment. The researchers ...

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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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