Pi Day References Images Pi Day observance Ask Anything Homework Help Written by The Information Architects of Encyclopaedia Britannica The Information Architects maintain a master list of the topics included in the corpus of Encyclopædia Britannica, and create and manage the relationships between them. The Information Architects of Encyclopaedia Britannica Britannica AI Ask Anything Learn about this topic in these articles: What Is Pi Day?Pi Day is a celebration of the never-ending mathematical constant pi (π), which relates the circumference C of a circle to its diameter d; that is, π = C/d.The numerical value of pi to five decimal places is 3.14159; hence, Pi Day is… Read MorePi Day is a celebration of the never-ending mathematical constant pi (π), which relates the circumference C of a circle to its diameter d; that is, π = C/d.The numerical value of pi to five decimal places is 3.14159; hence, Pi Day is… Read More