What is Pi? Pi (π) is the sixteenth letter of the Greek alphabet. It represents the ratio of a circle’s circumference (the length around the circle) to its diameter (the length from one side through the middle to the other side). Regardless of the size of the circle, pi is always the same number. You can find the number pi …

## Tippin’s Celebrates Pi Day at Science City

All About Pi It’s a Greek letter and an irrational number. It’s the ratio of a circle’s circumference to its diameter. And it’s a cause for celebration… it’s Pi! Even though it’s one letter short of the real thing, Tippin’s loves to celebrate Pi Day on March 14. This date is special because the value of Pi = 3.14… and …