Back in 1999, when I was an undergraduate, my math friend Dan Bruner and I decided that an appropriate Pi Day celebration would be to write as many digits of pi as we could on the sidewalk for everyone to see. We used really big digits and didn't have very much chalk, but we wrote about 888 (going from Wean Hall to the University Center) starting at 1:59AM, with our fingers freezing and our lungs wheezing at the end. In the following years we did the same, with more and more volunteers (once, our work was snowed on before daybreak!), each year doubling the number of digits that we wrote, and also starting a bit earlier in the night and writing smaller. (Dan eventually graduated but I still organized some pi writing as a PhD student.) In 2003 we got 8192 digits with the help of about 20 people, which I thought of as the pinnacle of pi writing. Unfortunately CMU moved its spring break to overlap Pi Day in 2004, and with most of my undergraduate friends graduated and most of my graduate friends working on their theses, I thought that would be the end of our chalking exploits. But in 2005, some mysterious pi ninjas unknown to me doubled the record to an amazing 16384 digits! The tradition lives on anonymously, at least when spring break does not interfere. If you have some information or pictures about missing years below, please email Tom!

1999: ~888 digits
2000: 1024 digits
2001: 2048 digits
2002: 4096 digits
2003: 8192 digits
2004: (cancelled)
2005: 16384 digits (courtesy of the mysterious pi ninjas)
2006: ?
2007: ?
2008: ?
2009: ?
2010: ?
2011: 1155 digits (unknown colorful pi volunteers)

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