I won't blame you for your error, only the BBC for their editing of the actual comment that Bailey stated: "at the very least we have shown why the digits of pi and log(2) appear to be random: because they are closely approximated by a type of generator associated with the field of chaotic dynamics." It does rather change the meaning of the quote, doesn't it. I.e. The numbers of pi can be approximated by a system that is associated with chaotic dynamics. It does not mean that pi itself is chaotic (it is just a number) but that systems (including trying to understand what the next digit is from what has gone before) involving pi can be. Furthermore, when they refer to the digits of pi being "random" they mean it in a statistical sense: each digit will appear 1/10th of the time, each pair of digits 1/100th of the time etc. I.e. That the number is "normal", and what they have been trying to do is actually prove that pi is such a number. But you are correct, the sequencing of the digits of pi can be used in a system if you are going from one to the next, because you are not just taking a constant (pi) but introducing a dynamic... moving from one digit to the next. The same way a brick can be used in a system, but the brick itself not being a system.