* <https://skanthak.homepage.t-online.de/division.html>
* <https://news.ycombinator.com/item?id=26562819>
* <https://gmplib.org/~tege/division-paper.pdf>
+* <https://github.com/Richard-Mace/huge-integer-class/blob/master/HugeInt.cpp> nice-looking well-commented c++ implementation
the most efficient division algorithm is probably Knuth's Algorithm D (with modifications from the exercises section of his book) which is O(n^2) and uses 2N-by-N-bit div/rem