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--- credit_card_numbers [2025/06/22 10:00] – frchris
+++ credit_card_numbers [2025/06/22 11:15] (current) – [Generating Credit Card Numbers] frchris
@@ Line 1: / Line 1: @@
 ====== Credit Card Numbers ======
-Credit card numbers are not random.  They use something called [[https://en.wikipedia.org/wiki/Luhn_algorithm|Luhn' Algorithm]] to make sure a customer or a clerk hasn't made a mistake typing in the long 16 digit number.  Here is a [[https://www.youtube.com/watch?v=Djt-KjciW20|video that explains how it works]]
+Credit card numbers are not random.  In addition to bank and account number there are extra digits.
+a customer or a clerk hasn't made a mistake typing in the long 16 digit number. In fact even magnetic strip fail, and errors in transmission from a chip reading devices can also fail to send the correct number.
+They use something called [[https://en.wikipedia.org/wiki/Luhn_algorithm|Luhn' Algorithm]] to detect errors. Here is a [[https://www.youtube.com/watch?v=Djt-KjciW20|video that explains how to see if a credit card is valid]].
+For this lab, we will write and test the validity of a 16 digit credit card.
+===== Generating Credit Card Numbers=====
+The practice of TDD (Test Driven Development) starts with writing the code to test our Validity software.
+This means we need to get some valid and invalid numbers and see if our code can spot the difference.
+Here is a [[https://www.youtube.com/watch?v=biFXw8zIyHs|video that explains what we need to do]]
+===== Checking with Luhn's =====
+===== Finding a Better Way =====
+[[https://www.youtube.com/watch?v=yaoSdFAL4UY|The Verhoeff-Gumm Check Digit Algorithm]]