Pi day: Celebrate Pi Day 2025

Celebrate Pi Day 2025 on March 14! Discover the significance of pi (π) in math, its history, and fun celebration ideas. Pi (& pi ;) is a constant describing the ratio between a circle's circumference and its diameter. Learn how pi was first calculated, why it is so popular, and how it is celebrated worldwide on March 14. Pi Day is an annual opportunity for math enthusiasts to recite the infinite digits of Pi , talk to their friends about math, and eat pie. Learn more about Pi , its history, its calculation, and its applications on Piday.org, a test preparation company. Learn about the number pi , why it is important in math, and what it is used to calculate!