In his experience, the answer to that question is a very succinct 'six and a lot of auxiliary back-up'.

"As many as would be willing," he parries instead. "Which I assume must not be many, or you wouldn't be planning things out this way."

He's not sure if he's irritated or not by the comparisons on the board, or by how she managed to draw and point so perfectly while blindfolded, but at the very least if it's true (he'd like to test that, himself) it provides a good deal of perspective on the situation before them.