Pi is the ration of the circumference of a circle to its diameter.It rounded up because the actual ratio has been calculated to over one trillion digits beyond the decimal point.The symbol for Pi(π) was first used in 1737 bt swiss mathematician Leonhard Euler.
            Pi day is observed on March 14,it is observed on the basis of month,day on date format,since 3,1 and 4 are the first three significant digits of π.
        What can i do to celebrate..?
             NASA wants you to celebrate,like a rocket scientist and  issued  a Pi in the sky challenge.It presents a series of math problems NASA engineers and scientists might solve by using Pi,such as how much of earth would be covered by an eclipse or how many days the Cassini spacecraft will need to orbit around Saturn.
            You can pay tribute by providing your own "Pie Day".
            Next year the pi day is celebrated on March 14th,2018.