> Evaluating different solutions leads to natural questions about the definitions implicit in the problem statement: mathematically, what is digit length?
OF COURSE! This is a MATHEMATICAL problem that is posed as a PROGRAMMING question. This has always confused me and I could never justify until reading this article why I felt them to be irrelevant to showcasing my programming knowledge. At the very least just tell people, this is the mathematical reasoning behind it, and watch the person implement it.