I revisited the OTN site again this morning and after few research I found out the promotional code you need to mention at registration time. But the code I found is not a 9 digit number. It's a 3 charater string { S36 }. To get to this code you have to login to OTN and attempt to download
the FREE OCP On-line Starter Kit. (If you are already a member, the server will tell you that you already have an account and give you an option to fill out a small 4 line survey. Fill out that survey and you will be taken to the discount screen) It looks something like this:

"Sign Up For a Test Now
Register for Oracle certification testing (mention promotional code"S36" to receive your OTN 20% discount) ..."