With the genuine enthusiasm that will bring out the inner nerd you never knew you had, watch as Portland State Professor of Mathematics John Caughman shows us why pi is so much more than an irrational and transcendental array of numbers.

**What IS pi?**

Pi is the ratio of the perimeter of a circle to its diameter. The number in decimal form is nonterminating and non repeating. Because it’s not exactly equal to any ratio of whole numbers, it’s called irrational. Because it is not exactly equal to the solution of any polynomial equation with whole number coefficients, it is called transcendental.

**How many digits of pi do we really know?**

On Aug. 14, 2021, a team at the University of Applied Sciences in Switzerland computed pi to 62.8 trillion digits. This was an improvement over the previous record of about 50 trillion digits, which had been set a little over two years earlier. According to Guinness, the world record for memorizing digits of pi is 70,000 held by Rajveer Meena of India, set in 2015.

**Portland’s MAX mistake**

If you take the MAX train to the Washington Park station, the first 106 digits of pi are carved into the station wall. But there’s a mistake that only increases John’s enjoyment of the unique charm of Portland.

And finally â€¦ after years of research, John shares the mystery of the last digit of pi!

Happy Pi Day, everyone! **Ï€**