Check If Credit Card Numbers Is Valid Or Not: Luhn Algorithm

I'm not sure how true it is. I dint verify.. You can check it out!
Luhn algorithm - Wikipedia, the free encyclopedia
Luhn algorithm
Now, the question is how can we check whether a given credit card number
is valid. The algorithm involved in this checking is called Luhn
algorithm (AKA Sum10 algorithm, AFAIK). Consider a number, say,
5168254236021548. To understand if this is a valid cc#, you should
follow 4 easy guidelines:
1. Starting from the leftmost digit, we simply multiply alternating
numbers by two. i.e., we multiply shown bold numbers by two:
5168254236021548
5 * 2 = 10
6 * 2 = 12
2 * 2 = 4
4 * 2 = 8
3 * 2 = 6
0 * 2 = 0
1 * 2 = 2
4 * 2 = 8
2. Add the separate digits of all the products, as follows:
1 + 0 + 1 + 2 + 4 + 8 + 6 + 0 + 2 + 8 = 32
3. Add the unaffected digits to the product, i.e.,
1 + 8 + 5 + 2 + 6 + 2 + 5 + 8 = 37
4. Add the result of the step 2 and 3 and divide it by 10
32 + 37 = 69
69 % 10 = 9
5. If the answer is 0, this is a valid cc#, otherwise, it is not!
So 5168254236021548 is an invalid cc# (since 69 % 10 is 9 not 0).

I don't think its true.... or may be I am doing the wrong calculation, because my Credit Card is coming as an Invalid Number....
Any suggestions?

Dear Swati,
As i said i've not checked it as of now, so better if i keep my mouth shut on this.
Let's others also try and post their experiences.
Till then keep trying :)

Credit card numbers are not assigned at random. Each number, usually 16 digits long, must adhere to certain mathematical conditions to be valid. This is called the Luhn Check, and it is used by almost all major cards. If you support a Web site that accepts online payments, the first step in any process that accepts credit card numbers should be verifying the number. This tip shows how you can do this using VB6.
Using VB6, the credit card number is passed, as a string, to the function CCNumberValid. The string must contain only digits—no embedded spaces or dashes. The function returns True if the number is valid and False if not.