I use the project as an opportunity to try learn new tools, and sometimes rely on features of a different language. Here's my breakdown of solved problems: 63 in Python (I solved the early problems while learning Python) 34 in C++ (when my old hardware was not fast enough) 13 in Ruby (when date functions were especially helpful) 13 in C# (slow days at work) 2 in Excel (shame!) 1 in Rexx (showing off) I admit I find it difficult to believe that many of the problems beyond the first few dozen could be solved on paper, but I have learned that there are often clever shortcuts. Working through the Chakravala algorithm on paper was a sublime experience. I boasted to a friend that I had solved #24 on paper; he responded by solving it in his head. My "friend key" is 16971_95168666b3371fa8a7b6548b677ce57c in case you care to observe my progress.