One of my big thrills at Lotusphere/Connect 2013 this year was a few seconds of microphone time at the Closing Session on Thursday afternoon.

John Hodgman was interviewing Steven Strogatz about mathematics and his book *The Joy Of X*, and the discussion came around to the statement that the number one is actually equal to the number 0.99999... repeating infinitely. Steven Strogatz asked if anyone in the audience had a "favorite proof" of this and, well, I indeed have one.

So I got to stand up, find a microphone, and stumble quickly through the proof. I was amazingly nervous -- being on a mic in a room with a few thousand people explaining a math proof to a well-known mathematician will make you nervous, as it turns out -- and I feel like I wasn't very clear about the whole thing, but John Hodgman made some very funny "WHA?" noises and both men on stage seemed to understand what I was saying and roll with it. And people clapped. So all in all it was a win.

The proof goes like this:

I've always thought that was a neat equation, and quite frankly it's about all I remember from my infinite series and sequences class in college. Math is cool.