# Questions tagged [checksum]

A checksum is a small chunk of data calculated from another larger piece of data, used to detect any transmission errors in the data. Use this tag for questions related to calculating or verifying checksums. (See also hashing)

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### The Luhn algorithm for verifying credit card numbers, etc

Challenge Write the shortest program or function to calculate the Luhn Algorithm for verifying (credit card) numbers. Luhn algorithm explained From RosettaCode, this algorithm for the purposes of ...
6k views

### Is my barcode valid?

An EAN-8 barcode includes 7 digits of information and an 8th checksum digit. The checksum is calculated by multiplying the digits by 3 and 1 alternately, adding the results, and subtracting from the ...
5k views

Background Adler-32 is a 32-bit checksum invented by Mark Adler in 1995 which is part of the widely used zlib library (also developed by Adler). Adler-32 is not as reliable as a 32-bit cyclic ...
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### Calculate ISBN-13 check digit

Write a function which, given the first 12 digits of an ISBN-13 code, will calculate the entire ISBN via calculating and appending an appropriate check digit. Your function's input is a string ...
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### For what block sizes is this checksum valid?

The input: As an example, take a list containing a number of bits (in this case, 32): 11000010000100111011000011001011 We can calculate a simple checksum of this ...
4k views

### Converting ISBN-13 to ISBN-10

Introduction In this challenge your task is to generate the ISBN-10 code for books given its ISBN-13 code, assuming that such a code exists. Such an ISBN-13 code consists of several parts separated ...