<Tr> <Td> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> </Td> </Tr> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> <P> Pi Day is an annual celebration of the mathematical constant π (pi). Pi Day is observed on March 14 (3 / 14 in the month / day format) since 3, 1, and 4 are the first three significant digits of π . In 2009, the United States House of Representatives supported the designation of Pi Day . </P> <P> Pi Approximation Day is observed on July 22 (22 / 7 in the day / month format), since the fraction ​ ⁄ is a common approximation of π, which is accurate to two decimal places and dates from Archimedes . </P>

When did the u.s. government recognize pi day as a holiday