The only unbreakable code (Score 1)

The fact that you can encrypt numbers with a set of random digits by adding your message to the random number is pretty standard - as far as I know, it's the only unbreakable code. You just use a different sequence of random numbers each time. Create two copies of the sequence, give one to the person you will want to eventually decrypt your message, and you're golden. Adding the offset-from-pi thing makes the code WAY less secure. Let's say you start your message with the offset from pi: 3746 2944 2345 or whatever, with the first four numbers being the offset, say. Now all your enemy has to do is figure out that you're using pi, and you're done for. So that's not an unbreakable code at all. An offset from pi is, after all, not a random number, it's a known one. Incidentally, this is sort of like that AOL thing a couple of days ago - if you want to maintain connection with our servers, you have to send us a message encrypted from a specific offset off of the aol.exe file! So to connect with AOL at all, you need AOL's executable. But, of course, an offset off of PI is easier to come by...