π=3. 14、2π=6.28、3π=9.42、4π= 12.56、5π= 15.7

6π= 18.84、7π=2 1.98、8π=25. 12、9π=28.26。

π is the ratio of pi, circumference and diameter. Generally expressed by the Greek letter π, it is a universal mathematical constant in mathematics and physics. π is an infinite acyclic decimal, which is approximately equal to 3. 14 1592654.

Extended data

π first appeared in Egypt in history. 1858, an antique dealer in Scotland stumbled upon the value of π written on papyrus (a writing medium widely used by ancient Egyptians).

The ancient Babylonians calculated that the value of π was 3. But the Greeks wanted to calculate the exact value of π further, so they drew a polygon in a circle. The more sides a polygon has, the closer it is to a circle.

The Greeks called this calculation method "exhaustive method". In fact, this really exhausted many mathematicians. Archimedes' geometric calculation results have a longer life. He estimated that the value of π was between 3 and 3. 17 through a 96-sided polygon.

In the next 700 years, this value has been the most accurate value, and no one can go any further. In the 5th century A.D., China mathematician and astronomer Zu Chongzhi and his son drew a polygon with 24,576 sides on a circle, and calculated the pi value between 3. 14 15926 and 3. 14 15927, which made the value of π go a step further.

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