What Day Is Pi Day 2024. Whether you're challenging yourself to find how many decimal placements are. Pi (greek letter “ π ”) is the symbol used in mathematics to represent a constant — the ratio of the circumference of a circle to its diameter — which is approximately 3.14159.
March 14, national pi day, honors 3.14 (π) the ratio of the circumference of a circle. Pi day is march 14, 2025 (3/14).