Your number to me right now is 4, because you're the 4th unique poster to post in this thread and therefore register themselves.
We will have more than 30 posters playing, so once the numbers are ran through a randomizer (random.org), the first 30 numbers that come out represent the actual wrestlers 1-30 in one set, the numbers 31-60 represent wrestlers 1-30 in the second set, etc.
Since we'll have a group of numbers that don't add up to 30, obviously, let's say 64 players...I'll take 61-64 (which, after randomized, would be something like 45, 42, 7, 18) and randomly generate a number 1-30 for them. So the 45th unique poster in the thread - AKA the 61st number on the randomized list - is not just number 1 in the straggler set - they could be 27. No repeats, of course...the randomizer would simply be run again.
I did a prelim run with that scenario...
Your number 4 -
just in this example only, of course - would have been the 6th entrant in the first Royal Rumble set.
tl;dr version - All this makes your entrant number
entirely random. Just like the wrestlers hoped to randomly get a favorable number, you will hope to randomly get a favorable number too...the winner.
If your entrant number becomes the Royal Rumble 2013 winner, you win 5,000 Coli Cash.