The World Pi Day has just been concluded but a lot of people might not know that the representation for one of the most important numbers in mathematics did not come from Greece but from an 18th century Welsh farm boy who taught himself math.

Pi is the number we use to calculate the circumference and area of a circle from its diameter and vice versa. History tells us that pi had been used as early as the ancient Egyptian times and encompasses different scientific disciplines from astronomy to thermodynamics.

It is interesting to note, however, that although ancient mathematicians had been using it through the years, even accurately calculating it to over 100 decimal places, they haven't really thought of a symbol that will represent it. Instead, mathematicians used a very long Latin definition to express 3.14: quantitas in quam cum multiflicetur diameter, proveniet circumferencia, which means the quantity which yields the circumference when you multiply the diameter with it.

Other expressions used to represent pi before the symbol π was used were 22/7 and 355/113 giving the impression that it was a rational number.

This all changed when a self-taught Welsh mathematics teacher, William Jones, used the symbol π in his second book called Synopsis Palmariorum Matheseos or New Introduction to Mathematics in 1706. Jones suspected that the numbers after the decimal point were non-repeating, infinite, and can never be expressed in number. Because of that, he recognized that the number needs to have a symbol of its own.

Why did he choose the symbol π to represent the number. There's a long-held belief that he chose this because it's the first letter of the word periphery or perimeter but no one was really sure about this claim.

Jones' book became a mathematical success and he became an influential member of the scientific establishment during that day. He also became friends with Sir Isaac Newton and Sir Edmund Halley.

However, the π symbol only enjoyed popularity when Swiss mathematician Leonhard Euler in 1737.