With the faintest snap of impatience, Sirius says, "I don't have the precise formula -- if I did, I would have said. Anyway, none of that matters if you haven't made any progress with the one thing I unambiguously and unequivocally told you to pursue. Have you tried to make any progress in that regard?#" It is very clear from Sirius' tone that if Q expects Sirius to devote any more of his attention to this, the answer had better be 'yes'.
#Can Q put it together from what Sirius has said here, and what I've said in email? This is partly Sirius' way of checking whether Q was paying attention, and since it was the only thing Sirius could state outright as being necessary to the prep., he's not going to give Q any more of a clue here until he knows whether Q Got It or not.