Python:  Validate Credit Card Numbers Using While Loops (Ep. 1)
Channel: Christian Hur
Date: 2020-10-04

⭕ Overview
In this video tutorial, I'm excited to walk you through creating a Python program to validate credit card numbers. This application checks whether a credit card number is valid, using the basic principles of a checksum formula tailored to credit card verification.

We will focus specifically on handling eight-digit credit card numbers, though the concepts can be easily expanded to the more common sixteen-digit numbers. The key part of our discussion will involve understanding and implementing the check digit, which is crucial for the verification process.

By the end of this tutorial, you'll have developed a functional Python program that can determine the validity of a credit card number. This skill is not only practical but also introduces you to algorithms commonly used in data validation and financial security.

☑️ The last digit of a credit card number is the check digit, which protects against transcription errors such as an error in a single digit or switching two digits. The following method is used to verify actual credit card numbers but, for simplicity, we will describe it for numbers with 8 digits instead of 16:

☑️ Starting from the rightmost digit, form the sum of every other digit. For example, if the credit card number is 4358 9795, then you form the sum 5 + 7 + 8 + 3 = 23.

☑️ Double each of the digits that were not included in the preceding step. Add all digits of the resulting numbers. For example, with the number given above, doubling the digits, starting with the next-to-last one, yields 18 18 10 8. Adding all digits in these values yields 1 + 8 + 1 + 8 + 1 + 0 + 8 = 27.
Add the sums of the two preceding steps. If the last digit of the result is 0, the number is valid. In our case, 23 + 27 = 50, so the number is valid.

☑️ Some sample valid numbers to try:
41235680, 12345674, 98765431, 11224458, 45645645

☑️ Write a program that implements this algorithm. The user should supply an 8-digit number, and you should print out whether the number is valid or invalid. 

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⭕ Chapters
  0:00 - Introduction

⭕ About me
I am a Web instructor and author for Linkedin Learning (formerly Lynda.com), Packt, E-C Council, Udemy, and MC Press.

⭕ Visit my site: https://christianhur.com
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