Why is Pi Day celebrated today, 14 March?

In the international calendar of unusual events to celebrate, this Tuesday (14 March) is reserved for what is surely one of the most popular mathematical concepts in the world. It is the result obtained by dividing the circumference of a circle by its diameter. This quotient always results in the number Pi: ​​3.1416 in its short version, since this digit is irrational and therefore with an infinite number of decimals, of which more than 22 billion are currently known.

Because it is the date that joins the two best-known decimals of Pi and the way in which the day and month (3/14) are written in the United States, where this event originated. In fact, it was the US House of Representatives that approved the creation of this day in 2009, which also coincides with the birth of the famous physicist Albert Einstein in 1879.

The symbol with which -π- is represented is the sixteenth letter of the Greek alphabet as well as the first letter of the Greek word periphereia, a term used to designate the perimeter of a circle.

The US space agency Nasa uses 16 digits of Pi to calculate exact positions, and on long-haul flights, where planes make an arc of a circle, the route is calculated using the Pi number to optimise the trip and fuel.

It was first used by the mathematician William Jones in 1706 and later popularised by the great mathematician and physicist Leonhard Euler, around 1734, who was the first to work out its value. The symbol π was adopted three years later, in 1737. In 1988, physicist Larry Shaw, working at the San Francisco Exploration Museum, had the idea of ​​promoting this anniversary.

The current record for memorising decimals of the number Pi is held by Suresh Kumar Sharma from India, who was able to recite a total of 70,030 decimal places in 2015. It took him more than 24 hours to do it.