I was finishing up my run today, listening to the book Thinking, Fast and Slow and the author asked the listener to multiply 17×24. I immediately “knew” that the answer was close to 4,000 (which is totally wrong), but the pretty incredible part is that after the author asked the listener to really stop the book and do the multiplication and I went to do so, I could not for the life of me remember how to do the multiplication. (granted I was running, so that was probably taxing my working memory a bit, but still, I have chemical engineering and MBA degrees… I should remember how to multiply as I’ve done so thousands of times in my life….). I couldn’t do it, and was fascinated by it. I got home, started stretching, and was still feeling confused and not confident I was doing things right in my head. Then I sat down with a piece of paper and it did come back to me then. I don’t know how much the running tripped me, but I was fascinated that I couldn’t remember how to multiply unless I sat down and had a pen and piece of paper in front of me.