I think of the number of yards of net in Miss Murdstone's cap, or of the price of Mr.
Murdstone's dressing-gown, or any such ridiculous problem that I have no business with, and don't want to have anything at all to do with.

Mr.
Murdstone makes a movement of impatience which I have been expecting for a long time.

Miss Murdstone does the same.

My mother glances submissively at them, shuts the book, and lays it by as an arrear to be worked out when my other tasks are done.
There is a pile of these arrears very soon, and it swells like a rolling snowball.

The bigger it gets, the more stupid I get.