Each week, I'll be choosing four or five of the most fun and interesting problems (in my opinion) I see in the community and posting them in a set. I'll be keeping an eye on the solutions, and at the end of the week will do a writeup on those I find exemplary. I'll also point out interesting things about the topics and where possible, show how to extend the thinking to more general situations.
Here is the first set
I hope you enjoy my selections and get something out of working on them. I'm looking forward to seeing everyone's work.