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author | Andinus <andinus@nand.sh> | 2021-08-11 15:26:15 +0530 |
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committer | Andinus <andinus@nand.sh> | 2021-08-11 15:26:15 +0530 |
commit | 321825828ac918bad28d0597a8616c6dc9802c3c (patch) | |
tree | 0b8e9cb1012197750eb58e972736319b2a6abac2 /raku/luhn/README.md | |
parent | 2979ef790ac5b8f58495e0dd08cafd6a3a2e30a5 (diff) | |
download | exercism-321825828ac918bad28d0597a8616c6dc9802c3c.tar.gz |
Add solved exercises
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diff --git a/raku/luhn/README.md b/raku/luhn/README.md new file mode 100644 index 0000000..fe6eb3a --- /dev/null +++ b/raku/luhn/README.md @@ -0,0 +1,88 @@ +# Luhn + +Given a number determine whether or not it is valid per the Luhn formula. + +The [Luhn algorithm](https://en.wikipedia.org/wiki/Luhn_algorithm) is +a simple checksum formula used to validate a variety of identification +numbers, such as credit card numbers and Canadian Social Insurance +Numbers. + +The task is to check if a given string is valid. + +Validating a Number +------ + +Strings of length 1 or less are not valid. Spaces are allowed in the input, +but they should be stripped before checking. All other non-digit characters +are disallowed. + +## Example 1: valid credit card number + +```text +4539 3195 0343 6467 +``` + +The first step of the Luhn algorithm is to double every second digit, +starting from the right. We will be doubling + +```text +4_3_ 3_9_ 0_4_ 6_6_ +``` + +If doubling the number results in a number greater than 9 then subtract 9 +from the product. The results of our doubling: + +```text +8569 6195 0383 3437 +``` + +Then sum all of the digits: + +```text +8+5+6+9+6+1+9+5+0+3+8+3+3+4+3+7 = 80 +``` + +If the sum is evenly divisible by 10, then the number is valid. This number is valid! + +## Example 2: invalid credit card number + +```text +8273 1232 7352 0569 +``` + +Double the second digits, starting from the right + +```text +7253 2262 5312 0539 +``` + +Sum the digits + +```text +7+2+5+3+2+2+6+2+5+3+1+2+0+5+3+9 = 57 +``` + +57 is not evenly divisible by 10, so this number is not valid. + +## Resources + +Remember to check out the Raku [documentation](https://docs.raku.org/) and +[resources](https://raku.org/resources/) pages for information, tips, and +examples if you get stuck. + +## Running the tests + +There is a test suite and module included with the exercise. +The test suite (a file with the extension `.rakutest`) will attempt to run routines +from the module (a file with the extension `.rakumod`). +Add/modify routines in the module so that the tests will pass! You can view the +test data by executing the command `raku --doc *.rakutest` (\* being the name of the +test suite), and run the test suite for the exercise by executing the command +`prove6 .` in the exercise directory. + +## Source + +The Luhn Algorithm on Wikipedia [http://en.wikipedia.org/wiki/Luhn_algorithm](http://en.wikipedia.org/wiki/Luhn_algorithm) + +## Submitting Incomplete Solutions +It's possible to submit an incomplete solution so you can see how others have completed the exercise. |