The Credit Card Project

re: The Credit Card Project

emma — Tue, 15 Mar 2011 12:21:06 GMT

hi i m appreciate for for youe thoughts.

re: The Credit Card Project

Alfred Thompson — Mon, 07 Mar 2011 16:53:20 GMT

For some fun with US social security numbers take a look at www.lavasurfer.com/.../socialsecurity.html

re: The Credit Card Project

Ben Chun — Fri, 04 Mar 2011 04:25:22 GMT

CS Unplugged includes a similar exercise illustrating how an ISBN checksum works:

csunplugged.org/.../unplugged-04-error_detection.pdf

NCTM Illuminations also combines ISBN and credit card validation in a lesson:

illuminations.nctm.org/LessonDetail.aspx

re: The Credit Card Project

Keith Ratliff (Dracorat) — Tue, 01 Mar 2011 23:44:55 GMT

One final note:

An easy number that checks out is this one:

4444 3333 2222 1111

Try it and see. =)

(Makes entering tests easy anyway)

re: The Credit Card Project

Keith Ratliff (Dracorat) — Tue, 01 Mar 2011 23:39:58 GMT

I just wrote up a C# solution for checking 16 digit numbers with this algorithm:

http://codepad.org/Kcw9KTjx

Critiques and questions always welcomed.

re: The Credit Card Project

Keith Ratliff (Dracorat) — Tue, 01 Mar 2011 23:09:10 GMT

Btw - the card number pictured on the card validates (ends with a 2) but when he does the math part and says =70 he ended the number with a 3. If you add all the digits according to form, you'll see it adds to 71. =)

re: The Credit Card Project

Doug Peterson — Tue, 01 Mar 2011 18:50:44 GMT

Thanks for sharing your thoughts about the little program, Alfred. As you note, this is just a simple little first blush at security. Hopefully, the Thompson millions are protected by more than a piece of software that I could write. I look forward to seeing your code and solution for the problem.