"No," said Herbert; "I know it's 'four cows,' but I can't get it."
"Sorry," I said, "how stupid of me; I left out the table-money."
I did it hastily again and made it three minutes twenty-five seconds.
"It is difficult, isn't it?" said Herbert. "I thought, as you used to be mathematical and as I'd promised the girl——"
"Wait a moment," I said, still busy with my envelope. "I forgot the subaltern. Ah, that's right. The answer is a hundred and twenty-five men.... No, that's wrong—I never doubled the half-crown. Er—oh, look here, Herbert, I'm rather busy this morning. I'll send it to you."
"Right," said Herbert. "I know I can depend on you, because you're mathematical." And he opened the door for me.
I had meant to do a very important piece of work that day, but I couldn't get my mind off Herbert's wretched problem. Happening to see Carey at tea-time, I mentioned it to him.
"Ah," said Carey profoundly. "H'm. Have you tried it with an 'x'?"
"Of course."
"Yes, it looks as though it wants a bit of an 'x' somewhere. You stick to it with an 'x' and you ought to do it. Let 'x' be the subaltern—that's the way. I say, I didn't know you were interested in problems."