I just downloaded Platform Builder 2.11 from the FTP, and when I installed it, it asked for a CD key... Nothing was in the archive (even a trial key), didn't find anything else on Google...

Saw a CD of Windows NT server (french version), with a key of the same size, and though: "Meh it would never work"... I gave it a shot anyway and HOLY CATS IT WORKED!

How is it possible? Do they all the same algorithm or I really got lucky?

BTW I tried with a random key, and it didn't accept... So it wasn't the software being bogus...

This is an especially common thing which happens with XXX-XXXXXXX style keys. I've used a vs6 serial before for three different unrelated MS products.

EDIT: And yes, there is an algorithm for those kinds of keys.

Yes, the algorithm is the same for all xxx-xxxxxxx keys. It's a stupidly easy algorithm as well; I once wrote a keygen that mass-generated valid xxx-xxxxxxx keys...

This key should also work:

IIRC, the "algorithm" is that the first part must be divisible by 3, the second part by 7.

Edit: Thanks linuxlove, it is the respective digit sum that has to be divisible.

I just tried it, but my key doesn't follow this logic...

Let me just add that you have to add the digits in each group together and then divide them.

Still, my two keys start with 040... But the second part is, in fact, divisible by 7