There are no "public" math clubs/circles/etcetera where we are. There are math clubs in some B&M schools, but our DS7 is not in a B&M school. I have thought about approaching the local gifted middle school about if he could sit in on their math club when he is "ready" (which is not yet). My concern is even if/when he's ready for the level of mathematics, he still might not be "ready" in pragmatic ways such as reading comprehension, writing output, classroom conduct etcetera. That's why I'm curious to hear about others' experience with this.