"Why, sir..."

"Well, you're not very good at subtraction."

"What makes you say that?"

"Because you don't know that nine minus eight equals one. And that, you
see, is a fact of the highest importance. Life becomes impossible if you
are ignorant of that fundamental truth."

He rose, as he spoke, and walked round the room, with his hands behind
his back, swaying upon his hips. He did so once more. Then, stopping
at the dining-room, he opened the door:

"For that matter, there's another way of putting the problem. Take eight
from nine; and one remains. And the one who remains is here, eh?
Correct! And monsieur supplies us with a striking proof, does he not?"

He patted the velvet curtain in which Lupin had hurriedly wrapped himself:

"Upon my word, sir, you must be stifling under this! Not to say that I
might have amused myself by sticking a dagger through the curtain.
Remember Hamlet's madness and Polonius' death: 'How now! A rat? Dead,
for a ducat, dead!' Come along, Mr. Polonius, come out of your hole."

It was one of those positions to which Lupin was not accustomed and
which he loathed. To catch others in a trap and pull their leg was all
very well; but it was a very different thing to have people teasing him
and roaring with laughter at his expense. Yet what could he answer back?