Pi Day Offers 2025. 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. Of course, the recipe for pi goes back centuries, but today look for national restaurant chains offering pizza for $3.14 a.

Want to calculate the circumference of a pie (or a pizza pie)? Since 3, 1 and 4 are the three most significant.