Yesterday was March 14 or 3/14 so it is national 𝛑 (Pi) day. This is celebrated because the first three digits of Pi are 3.14. Pi has this symbol 𝛑 because it is the Greek letter for p. “P” was used because of the perimeter of the circle. The symbol was first used in 1773 by Leonhard Euler. To this day Pi has been calculated to over one trillion digits which of only 39 digits after the decimal are needed.