March 14 is Pi Day, an annual celebration of the mathematical constant of pi, representing the ratio of a circle's circumference to its diameter. The holiday is observed on March 14 or 3/14 because 3.14 are the first three digits of the infinite number pi — 3.14159 ... and on and on.

A dangerous storm system is expected to sweep through the St. Louis region Friday evening, bringing the potential for destructive winds and fast-moving tornadoes, with the metro area under a Level 4 out of 5 risk for severe weather. Edward Coristine was most recently in his freshman year at Northeastern University, where he studied engineering.

From schoolkids learning about constant numbers to pizza deals to school serious math equations, here’s a slice of Pi Day fun.