>Here is a tabular response showing what happens. As you can see the
>rolls. In other words, the same result can be generated by multiple source
>numbers e.g. any palindromic number will yield 0. So getting an answer of 0
>leaves you no way to tell how it was generated - was it 999 or 101? There
>may be some interesting instant tricks based on memorizing the table as
>there are relatively few results.
Yeah, I got the same sort of thing working from a different approach. The answer is going to be something like: (the first digit - the last digit) x 99. The middle number drops out completely. So you could do something with what the first and last add or subtract to, but I don't see how you could get the middle number without having them do another equation as well.