Remember this number, 3.14159? It's Pi, the natural number that describes the mathematical properties of a circle. Well, the digits for Pi go on and on and on (for infinity actually) and that makes for some fun competitions and great feats of memory. As a matter of fact a 59-year-old Japanese psychiatric counselor, Akira Haraguchi, has recently broken the world record for reciting the digits of Pi from memory. From the time he started at 3.14 to the time he ended 13 hours later he recited 42,195 digits of Pi.
Can you imagine memorizing that many numbers? Check out the first 10,000 digits of Pi to see how hard it is to remember that many numbers. And if that doesn't wear you out, try for the record by checking out the first 100,000 digits of Pi.
To learn more about the fun aspects of Pi, check out the Exploratorium's Ridiculously Enhanced Pi Page. Every March 14th, international Pi day, in San Francisco the Exploratorium hosts a Pi festival with lots of fun activities, including real pie.
To learn more about human memory, check out the BBC's Human Body and Memory Tests website. You can explore some amazing facts about the human mind but also take a number of surveys to test your own memory.