section_heading: Klasično razdoblje
paragraph_text: William Jones' book A New Introduction to Mathematics from 1706. is cited as the first text where the Greek letter π was used for this constant, but this notation became particularly popular after Leonhard Euler adopted it in 1737.<ref> He wrote: <nowiki>There are various other ways of finding the Lengths or Areas of particular Curve Lines, or Planes, which may very much facilitate the Practice; as for instance, in the Circle, the Diameter is to the Circumference as 1 to (16/5 - 4/239) - 1/3(16/5^3 - 4/239^3) +&nbsp;...&nbsp;=&nbsp;3,14159...&nbsp;=&nbsp;&pi;</nowiki> -->