Johnpiper, I have just reached this part of the game where I have to put my maths skills to the test. I believe the "leading question" comprises three words, the last two of which are significant.
I never thought the answer to be shaded could be in the title! All along I’ve been toying with posing the question: “What is the prime number?” and wondering whether to answer: “hundred and three”. It seems I’ve been reading too much into it!
Matakari, sorry to hear you led yourselr astray, There's very little in the way of maths involved - and none for you now that you know what's to be shaded!