Article in English: This method won't work with ellipses, ovals or anything but a real circle. A circle is defined as all the points on a plane that are an equal distance from a single center point. The lids of jars are good household objects to use for this exercise.You should be able to calculate pi roughly because in order to get exact results of pi, you will need to have a very thin lead(or whatever you are using). Even the sharpest pencil graphite could be huge to have exact results. The circumference is the length that goes around the entire edge of the circle. Since the circumference is round, it can be difficult to measure (that's why pi is so important). Lay a string over the circle as closely as you can. Mark the string off where it circles back around, and then measure the string length with a ruler. The diameter runs from one side of the circle to the other through the circle's center point. The circumference of a circle is found with the formula C= π*d = 2*π*r. Thus pi equals a circle's circumference divided by its diameter. Plug your numbers into a calculator: the result should be roughly 3.14. This will give you more accurate results. Your measurements might not be perfect on any given circle, but over time they should average out to a pretty accurate calculation of pi.

Summary in Chinese:
找到标准的圆形物体。 尽量精确地测量圆的周长。 测量圆的直径。 使用公式。 为了得到更精确的结果，请使用多个不同的圆形物体重复上述步骤，然后取所有结果的平均值。