The only puzzle I haven't been able to solve is 12, though I was able to get the final solution without that one because I was close enough that it was just a guess between two options. But I want to solve 12! I thought I had the critical idea, but my answer was wrong. Maybe I could get a hint? I'd love to do a spoiler tag here to explain my original thinking, but I'm not sure how to do that...maybe I'll try a couple things below.
test
test
on /blog/107