In the olden days, all Danish children had to memorize the Danish monarchs. If they weren't able to remember, they would get beaten. You probably won't meet the same fate if you don't know them all, but give it a try anyways.
Regnal numbers must be used, unless an epithet is used instead. Use English versions of names, unless no English version exists.
Junior co-rulers only included during periods of disputed succession.
you should accept the Danish way of spelling the names also, I think.
I.e. John who is Hans in Danish, Sweyn who is Svend etc
I chose to not accept Danish spellings in this quiz because there is also a Danish version, but I might reconsider now that you suggest it.