I am saddened to say that Math Challenges has been closed by the Community Moderator, Robert Cartaino (prematurely). I'd like to thank everyone who have participated in the past three months of development, especially to those who have helped suggest ideas through meta posts. Proposing is not easy!
Surprisingly, no notice whatsoever was given. The one thing I agree with Robert is that the proposal surpasses the intended Q&A format, but wouldn't there be a chance that this could be fixed if he posted this two months earlier?
Please drop a message/answer to the meta post linked if you have any further thoughts.
It has come to my attention that there is a group of users in MSE (myself included) who want to share their own mathematical challenges.
Thus, I have made a proposal in Area 51: Math Challenges.
There have been previous debates on whether challenges/contests should be posted on MSE. Using this question and this one as examples, it can be seen that some people object, some are in favour, and some are in favour given some conditions they've proposed. I believe that this would be completely resolved if there were another site specifically for these types of posts.
A clear distinction between Puzzling SE and this (future) site is that the former site doesn't allow purely mathematical problems. For example, this post of mine was closed there, because "it appears to be a mathematics problem, as opposed to a mathematical puzzle."
Users who are interested in the creation, sharing and answering of mathematical challenges are more than welcome to follow the proposal. In the meantime, a bonus is that you can start thinking of challenge problems to be posted in the "example problems" section :)
If you wish to further discuss this, feel free to use this chatroom
Updates from Area 51 Discussions:
How will this community deal with homework type questions? answered + accepted
What to do with serial downvoting of my proposal? answered + accepted
Wording of Site Description unanswered