My mother taught me how to extract square roots manually, and I'm writing up a paper on how to do it for calculus. Meanwhile, we have a name for our team in the Bank's annual "Battle of the Brains" or "BoB". Just at the moment, I'm short of hours in the day. I'm heading for six hours of meetings and seminars today before I leave, apart from which there are a variety of papers to read and write, both bank and non-bank. But for now, it's a few minutes of train time, and quiet-ish reflection.