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  2. Barcode - Wikipedia

    en.wikipedia.org/wiki/Barcode

    A barcode or bar code is a method of representing data in a visual, ... A two-width, also called a binary bar code, contains bars and spaces of two widths, "wide" and ...

  3. Code 39 - Wikipedia

    en.wikipedia.org/wiki/Code_39

    The barcode scheme does not contain a check digit (in contrast to—for instance—Code 128), but it can be considered self-checking on the grounds that a single erroneously interpreted bar cannot generate another valid character. Possibly the most serious drawback of Code 39 is its low data density: It requires more space to encode data in ...

  4. Check digit - Wikipedia

    en.wikipedia.org/wiki/Check_digit

    A GS1 check digit calculator and detailed documentation is online at GS1's website. [5] Another official calculator page shows that the mechanism for GTIN-13 is the same for Global Location Number/GLN. [6] For instance, the UPC-A barcode for a box of tissues is "036000241457".

  5. Universal Product Code - Wikipedia

    en.wikipedia.org/wiki/Universal_Product_Code

    A UPC barcode. The Universal Product Code (UPC or UPC code) is a barcode symbology that is used worldwide for tracking trade items in stores.. The chosen symbology has bars (or spaces) of exactly 1, 2, 3, or 4 units wide each; each decimal digit to be encoded consists of two bars and two spaces chosen to have a total width of 7 units, in both an "even" and an "odd" parity form, which enables ...

  6. Calculator - Wikipedia

    en.wikipedia.org/wiki/Calculator

    The first handheld calculator was a 1967 prototype called Cal Tech, whose development was led by Jack Kilby at Texas Instruments in a research project to produce a portable calculator. It could add, multiply, subtract, and divide, and its output device was a paper tape.

  7. Calculator input methods - Wikipedia

    en.wikipedia.org/wiki/Calculator_input_methods

    On a single-step or immediate-execution calculator, the user presses a key for each operation, calculating all the intermediate results, before the final value is shown. [1] [2] [3] On an expression or formula calculator, one types in an expression and then presses a key, such as "=" or "Enter", to evaluate the expression.

  8. Luhn algorithm - Wikipedia

    en.wikipedia.org/wiki/Luhn_algorithm

    The Luhn algorithm or Luhn formula, also known as the "modulus 10" or "mod 10" algorithm, named after its creator, IBM scientist Hans Peter Luhn, is a simple check digit formula used to validate a variety of identification numbers.

  9. Glossary of mathematical symbols - Wikipedia

    en.wikipedia.org/wiki/Glossary_of_mathematical...

    A mathematical symbol is a figure or a combination of figures that is used to represent a mathematical object, an action on mathematical objects, a relation between mathematical objects, or for structuring the other symbols that occur in a formula.