# Number pi

**Number pi** - one of the most known numbers used in the natural sciences (mathematics, physics, engineering, etc.), for many millennia fascinated the minds of great thinkers and mathematicians. At school, we realized that the number pi is the ratio of the circumference to the diameter. William Jones (1675-1749) - English mathematician, the first designated it with a Greek letter. In 1737 this designation was borrowed by the Swiss mathematician Leonard Euler, and thus it became generally accepted.

If we get acquainted with the history of the pi number, we will see that the history of mankind will appear before us as a series of efforts by many mathematicians to determine the signs of the pi number and to find ways to calculate it. Behind these signs are the shadows of the greatest thinkers of the Ancient World and the Middle Ages, New and Newest Times. Throughout the history of studying the number of pi, up to our days, there was a kind of chasing after its decimal signs. In 1220, Leonardo Fibonacci identified the first three exact decimal places of pi, and in the 16th century. Andrian Antonis (Flemish mathematician) defined six signs. Antonis found the number pi with fifteen signs after the decimal point. Such a method of calculating the number pi-writing into the circle of a regular polygon and finding the ratio of its perimeter (i.e., the sum of the lengths of all its sides) to the radius-was first used by Archimedes. Therefore, the number pi is often called the Archimedes number. The same method used al-Kashi.

Information that the circle is exactly three times as long as the diameter, are already in the cuneiform tablets of the Ancient Mesopotamus. The same meaning of the number pi is in the text of the Bible. In the sacred book of Jainism (one of the oldest religions that existed in India and originated in the 6th century BC), there is one indication, from which it follows that the number of pi at that time was taken to be 3,162. But already in the second millennium BC. e. the ancient Egyptians used a more accurate meaning, which is obtained from the formula for the area of the circle. The area of the circle with diameter *d* Egyptian mathematicians was defined as (d - d/9)^{2}. It can be concluded from the above expression that at that time the number pi was considered equal to the fraction (16/9)^{2}, or 256/81, i.e., pi = 3,160.

This information was obtained from the so-called "Mathematical Papyrus" of Rhind found in 1858. It is known that this papyrus was copied by the scribe Ahmes around 1650 BC the author of the original is unknown - it is established only that the text was created in the second half of the 19th century. BC. This document remains the main source of information from the mathematics of Ancient Egypt. It contains drawings of triangles with directions of angles and formulas for finding areas, and also shows the division of number 2 into odd numbers from 3 to 101 in fractions and division of numbers from 1 to 9 by 10. However, to understand how the Egyptians received the very formula for calculating the number of pi, from the context is unclear. We give here the values of the number pi obtained by the ancient mathematicians: 16/9 = 3,1604 for the Egyptians; 22/7 = 3,1428 for the Greeks and 3,162 for the Hindus.

The exact value of the number pi can not be calculated, since it is irrational, that is, it can not be expressed in the form of a simple fraction. This, however, did not deter many well-known mathematicians from exhausting attempts to calculate as many values of pi as possible. In 1996 at the National Research Center in Berkeley Baylis and colleagues came to an amazing discovery, which allows to calculate any sign of the number pi without obtaining information about the senior ranks. Successful Japanese mathematicians used the proposed method of computation to verify the millionth sign of the pi number, and the formed group soon calculated the quadrillion sign!

The number of pi is one of the main features of our civilization and similar to us. This is the password of reason similar to ours. Civilization, which does not know the number of pi, does not have mathematics and radio engineering. Most likely, it developed so different from us that at this stage we just can not understand each other.