So its not like I dreamed this number up. But it does seem to be a bit more complicated of a question.
I find my MP thirst is quenched a bit with at least one person, thanks mb66energy, having the breakdown of how to go about thinking about it. And Canon-F1, having read 8-45mp, as least the 8 mp floor is somewhat established given what I think I remembered of 8Mp being the "standard or goal".
Interested to read others recollections or thoughts. Or facts