Serial number in the context of Unique identifier

A number is a mathematical object used to count, measure, and label. The most basic examples are the natural numbers: 1, 2, 3, 4, 5, and so forth. Individual numbers can be represented in language with number words or by dedicated symbols called numerals; for example, "five" is a number word and "5" is the corresponding numeral. As only a limited list of symbols can be memorized, a numeral system is used to represent any number in an organized way. The most common representation is the Hindu–Arabic numeral system, which can display any non-negative integer using a combination of ten symbols, called numerical digits. Numerals can be used for counting (as with cardinal number of a collection or set), labels (as with telephone numbers), for ordering (as with serial numbers), and for codes (as with ISBNs). In common usage, a numeral is not clearly distinguished from the number that it represents.

In mathematics, the notion of number has been extended over the centuries to include zero (0), negative numbers, rational numbers such as one half ${\displaystyle \left({\tfrac {1}{2}}\right)}$, real numbers such as the square root of 2 ${\displaystyle \left({\sqrt {2}}\right)}$, and π, and complex numbers which extend the real numbers with a square root of −1, and its combinations with real numbers by adding or subtracting its multiples. Calculations with numbers are done with arithmetical operations, the most familiar being addition, subtraction, multiplication, division, and exponentiation. Their study or usage is called arithmetic, a term which may also refer to number theory, the study of the properties of numbers.

Buran (Russian: Буран, IPA: [bʊˈran], lit. 'blizzard'; GRAU index serial number: 11F35 1K, construction number: 1.01) was the first spaceplane to be produced as part of the Soviet/Russian Buran program. The Buran orbiters were similar in design to the U.S. Space Shuttle. Buran completed one uncrewed spaceflight in 1988, and was destroyed in 2002 due to the roof collapse of its storage hangar at Baikonur Cosmodrome. The Buran-class orbiters used the expendable Energia rocket, a class of super heavy-lift launch vehicle. Besides describing the first operational Soviet/Russian shuttle orbiter, "Buran" was also the designation for the entire Soviet/Russian spaceplane project and its flight articles, which were known as "Buran-class orbiters".

A CAS Registry Number (also referred to as CAS RN or informally CAS Number) is a unique identification number, assigned by the Chemical Abstracts Service (CAS) in the US to every chemical substance described in the open scientific literature, in order to index the substance in the CAS Registry. This registry includes all substances described since 1957, plus some substances from as far back as the early 1800s. It is a chemical database that includes organic and inorganic compounds, minerals, isotopes, alloys, mixtures, and nonstructurable materials (UVCBs - substances of unknown or variable composition, complex reaction products, or biological origin). CAS RNs are generally serial numbers (with a check digit), so they do not contain any information about the structures themselves the way SMILES and InChI strings do.

The CAS Registry is an authoritative collection of disclosed chemical substance information. It identifies more than 204 million unique organic and inorganic substances and 69 million protein and DNA sequences, plus additional information about each substance. It is updated with around 15,000 additional new substances daily. A collection of almost 500 thousand CAS registry numbers is made available under a CC BY-NC license at ACS Commons Chemistry.

Casino chips (also known as poker chips, gaming tokens, or checks/cheques) are small discs used as currency in casinos. Larger, rectangular gaming plaques may be used for high-stakes games. Poker chips are also widely used as play money in casual or tournament games, are of numismatic value to casino chip collectors, or may be kept as souvenirs.

Chips and plaques used in table games may be made of a mixture of metal, clay, ceramic, and plastic materials inlayed or painted with colors and numbers indicating various denominations, while metal token coins are used primarily in slot machines. Some casinos embed RFID tags into chips to collect data and fight counterfeiting, and plaques may have printed serial numbers.

A form is a document which contains blank spaces (also named fields or placeholders) in which one can write or select an option. Forms can be distributed to several signatories at once, or made available on demand. Before being filled out, each copy of a form is usually identical, except, possibly, for a serial number. A form allows an organisation to collect a uniform set of data from many parties in a consistent manner.

Forms, when completed, vary in their purpose; for example, a form might be a statement, a request, or an order. A cheque may also be considered a form. In addition, there are several forms for taxes. An example is a tax return; filling one out is required in order for the amount of tax one owes to be determined. A form may also be a request for a tax refund.

A vehicle identification number (VIN; also called a chassis number or frame number) is a unique code, including a serial number, used by the automotive industry to identify individual motor vehicles, towed vehicles, motorcycles, scooters and mopeds, as defined by the International Organization for Standardization in ISO 3779 (content and structure) and ISO 4030 (location and attachment).

There are vehicle history services in several countries that help potential car owners use VINs to find vehicles that are defective or have been written off.

A key generator, commonly abbreviated as keygen, is a computer program that generates a product key and/or serial number necessary for product activation of an application software. Keygens may be legitimately distributed by software manufacturers for licensing software in commercial environments where software has been licensed in bulk for an entire site or enterprise, or they may be developed and distributed illegitimately in circumstances of copyright infringement or software piracy.

Illegitimate key generators are typically programmed and distributed by software crackers in the warez scene. These keygens often play music (taking from the tradition of cracktros), which may include the genres dubstep, chiptunes, sampled loops, or anything that the programmer desires. Such chiptunes are often made in music trackers, and are mostly preferred due to their small size. Such keygens can have artistic user interfaces or kept simple and display only a cracking group or cracker's logo.