William Jones was a Welsh mathematician who taught mathematics on board ship between 1695 and 1702. After his travels, he became a mathematics teacher in London. The symbol π (pi), which represents the ratio of the circumference of a circle to its diameter, was first used by William Oughtred in 1647. William Jones later used the symbol in his book

*Synopsis Palmariorium Matheseos*which was published in 1706. His book also included John Machin’s (1680-1751) calculations of the first 100 decimal places of π. Jones is believed to have used the Greek letter π because it was the first letter of the Greek word*perimetron*(περίμετρος] , meaning “perimeter”. The symbol was popularized by Euler in 1748.