Pi is expressed by the Greek letter π (pronounced pài), which is a constant (approximately equal to 3. 14 1592653), representing the ratio of circumference to diameter. It is an irrational number, that is, an infinite cycle decimal. In daily life, pi is usually expressed as 3. 14, which is used for approximate calculation.

Characteristics of pi:

It is of little practical significance to calculate the value of pi so accurately. A dozen pi values used in modern science and technology are enough. If the Hubble volume is calculated by using the 39-bit precision pi value, the error is less than the volume of an atom.

In the past, people calculated pi to explore whether pi circulated decimals. Since Lambert proved that pi is irrational in 176 1 and Lin Deman proved that pi is transcendental in 1882, the mystery of pi has been uncovered. π plays a very important role in many fields of mathematics.