Also 21 guesses but only a 33% hit rate. I've got some decent knowledge of the relevant topic.
DD hasn't forgiven me for the day I talked up the easiness of XXX and XXXXX and the fact that it was gettable in 2, and she struggled over it for ages before getting it in about 100. Her standard opening gambit is "war", which is very useful for anything historical, so if I hadn't said anything she'd have nailed it immediately.