Even people far from mathematics have heard of the number Pi. π is an infinite decimal fraction, its rounded value is 3.14.
The number "Pi" is very popular - journalistic books and scientific monographs have been written about him, films are made in his honor, paintings and sculptures are devoted to him. The constant is even played on musical instruments, but not everyone knows who invented such a name and why “Pi”.
The story of the appearance of the number "Pi"
The constancy of the ratio of the circumference of a circle to its diameter was noticed back in the antiquity. In Mesopotamia, a rather rough rounding of the number to 3 was used and it was used in the construction of the Tower of Babel. More precisely, as 3.16 π was designated by ancient Egyptian mathematicians.
For the first time, the calculation of "Pi" on a scientific basis was undertaken by the great ancient scientist Archimedes (287-212 BC), who came up with the idea of replacing the circumference with the perimeter of the 96-gon inscribed in it. The result is an Archimedean number - a fraction of 22/7 or 3.14286.
Interesting fact: π calculated with an accuracy of 31.4 trillion decimal places (for 2019).
The idea of William Jones
Amazing but the famous number until the XVIII century did not have a permanent name. In the Middle Ages it was often called "the number, which, when multiplied by the diameter, allows you to get the circumference". Another name - “Ludolph number” was given in honor of the Dutch scientist Ludolf van Zeilain (1540-1610), who managed to determine the value of the constant with an accuracy of up to 20 decimal digits. The numerical designations 355/113 and 22/7 were also used, which formed the illusion of the rationality of the number.
That all changed when the English mathematician William Jones (1675–1749) published the review of the achievements of mathematics in 1706, in which he used the Greek letter π for the now most famous mathematical constant. He was guided by simple logic - with the letter "pi" begins the word περιμετρ начинается, which means "measure around".
Interesting fact: π has its birthday, March 14th.
Interesting fact: π has its own language - in it the number of letters in words is identical to the digits of the number "pi" in a sequential order.
However, it is believed that Jones had previously seen the symbol π. His colleague William Otred (1575-1660) using the letter "pi" denoted the length of a particular circle, so the value was constantly changing. After Otred’s life, a number of his works and documents came to Jones, who gave π philosophical meaning. But the symbol π received wide distribution thanks to another, much more famous mathematician.
Euler's discovery
The famous German, Swiss and Russian scientist Leonard Euler (1707-1783) made a decisive contribution to understanding the arithmetic nature of the number π. He managed to determine the sequential series for his calculation. If you take 210 members of this series, you can get 100 correct signs π. Euler himself was able to determine the value of the constant with an accuracy of 153 decimal places.
Interesting fact: π is considered transcendental - there is no algebraic formula expressing π in terms of rational numbers.
Massively use the symbol π began around 1736 after Euler began to use it repeatedly in his works. Among them were works where a lot of statements related to the number of summable terms are given, which are required to determine the approximate indicator “pi” with a given accuracy.
Interesting fact: There is a pi club, the participants of which know thousands of digits of the memory.
People showed interest in the number “pi” even in antiquity, when they began to calculate its value. However, until the XVIII century it did not have a generally accepted name. The magnitude without a name has ceased to be a mathematical constant due to two mathematicians W. Jones and L. Euler. The first suggested the symbol π, and the second gave it wide distribution.
