407. Memorising Pi

March 14, is Pi day – a celebration of the famous mathematical constant Pi, 3.1415926535 … 

Pi is the ratio of a circle’s circumference to its diameter. It has an infinite number of decimal places, and there is no pattern to them, and no point where it starts to repeat. This makes it a challenge to memorise, which is presumably why memorising Pi has been such a popular pastime amongst people of a certain type. It is the ultimate nerdy challenge to see how many decimal places one can remember.

There is a website that lists people who have memorised Pi from all around the world. It shows the record for each country and globally, and other creditable attempts. The official world record is an astounding 70,030 decimal places, which took Suresh Kumar Sharma of India over 17 hours to recite in 2015.

There is also an unofficial record of 111,700 decimal places, by Akira Haraguchi from Japan, in 2006. It’s amazing what the human mind can do.

I had long known about this quirky hobby of people memorising Pi but had never been tempted myself. But on a whim, about a decade ago, I decided to give it a quick go, just to see how easy or hard it was. In a few hours, I was able to memorise 100 decimal places. I had no intention of doing more than that, but I found it was easy to add on a few more digits each day, so over time my string of memorised decimal places slowly grew.

It required regular reminders to keep the numbers in my memory, but I found mentally reciting Pi to be quite enjoyable and relaxing – a good thing to do when there’s nothing much happening. It was also interesting to see what my brain could do. It seemed to get a bit easier as I memorised more and more.

Eventually I memorised over 1,600 decimal places. That’s a tiny number compared with the world record, but I felt quite chuffed to have done that much. To get onto the official website, I had a couple of colleagues witness me reciting it. Here’s a video of me doing that in August 2020, and getting up to 1,609 decimal places.

That is sufficient to position me at number 9 in Australia and number 137 globally in the all-time lists.

After that successful attempt I stopped doing regular practice, and over time I steadily lost my ability to remember so many digits. Now I can remember 250 digits, but I’d have to do a heap of practice to get back to where I was in 2020. I’m satisfied with having done it back then.