Why did you start doing this?

Back in 2005, a new colleague joined us at South Bank University, Carrie Rutherford, who had impeccable mathematical credentials, so that was nice for me.

And then she started posting outside her office the Mathematician of the Day, which comes from an even older and better-known website called The MacTutor Archives History of Mathematics, which is based at St. Andrews University in Scotland.

If you don't know it, you should check it out.

It's a, a huge resource with hundreds and hundreds and hundreds of biographies of mathematicians.

And every day, they post a little poster, which you can print out and put up, with one of the mathematicians who were born or died on that day.

So Carrie used to post a mathematician every day, and I was jealous, and I thought, "I would like to post something outside my office." And so I started doing a Theorem of the Day to go with it.

Okay, good.