At the time when I had bills (go on with your drawing; you can listen, and draw too), I used, of course, to think it necessary to check the tradespeople, and see that their Total was right.

You will hardly believe me, but I don't remember ever making the sum what the shop made it, on more than about three occasions.

And, what was worse, if I tried a second time, I could not even get it to agree with what I had made it myself the first time.
Thank Heaven, I've no difficulties of that sort to grapple with now! Everything's paid for the moment it comes in.

If the butcher hands a leg of mutton to the cook over the airey railings, the cook hands him back six and nine--or whatever it is--and takes his bill and receipt.

I eat my dinners now, with the blessed conviction that they won't all disagree with me in an arithmetical point of view at the end of the year.