Some questions are still on web.archive.org.
Quote from dloserTo be honest, I don't really think it is worth much. The challenges as I remember them aren't that high quality (and some are simply bad).
I can remember, that some of the series questions had a wrong answer in the database - what explains the low solver numbers to the particular problems. overview
. I then looked in the forum to find an old post mentioning that - but it was still not fixed.
For another problem you had to enter a fraction - but not in reduced form.
and now MathChall is down too.