How I brush my teeth depends on the date.

I use an electric toothbrush that has a 30 second timer. You do a quarter of your mouth, it vibrates, you move on.* Years ago I realised that by always starting in the same quadrant I was favouring some teeth over others. Maybe I get lazy towards the end? Maybe each 30s segment isn't quite the same length? (I'm now convinced that the first is shorter.)

So I start with the quadrant that is the date modulo 4. 1st of the month? Top right (as I look out of my head). And then I work clockwise.

This has many advantages.

- You tend to remember the date.
- You brush all teeth equally.
- You learn how to divide any number by 4.

But it has one disadvantage! Which is that most months neglect the final (top left) quadrant, and half neglect the penultimate (bottom left).

EXCEPT FEBRUARY! So thanks, February, for finishing on the 28th. Top left. Tomorrow's the 1st. Top right. All is equal.

(*Compared to my old toothbrush, which vibrated after the 2 minutes was up, it's incredible how subjectively faster this time passes. Previously I'd often give up before the full 2 minutes had passed. Now I never, ever do. I strongly recommend this timer.)