1, π is pronounced pài, which means that pi is about 3. 14. It is used to calculate the circumference (area) of a circle and the surface area (volume) of cylinders and cones.

2.π characteristics: 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 value of pi with 39-bit precision is used to calculate the size of the universe, 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.