By The Conversation. We need just a little more party hat… Yelp/Flickr, CC BY-NC-ND Editor’s note: The following is a roundup of archival stories. On March 14, or 3/14, mathematicians and other obscure-holiday aficionados celebrate Pi Day, honoring π, the Greek symbol representing an irrational number that begins with 3.14. Pi, as schoolteachers everywhere repeat, represents…