The problem asks to implement code to increment a decimal number D to D+1. The solution doesn't apply to any decimal number, only decimal integers. Correct? And the problem is meant only for integers, not numbers?
If 129 meant 12.9 adding 1 with the given approach wouldn't work. I think it was slightly confusing as terms such as finite-precision or precision arithmetic seem to be usually associated with floating point numbers, not integers.