今天(3月14日)是一年一度的国际圆周率日。上学时，你一定背过3.1415926……你能背到小数点后多少位？

  什么是圆周率日？

  The maths event celebrates π, the term used to describe the ratio of a circle’s circumference to its diameter, commonly shortened to 3.14159. It has been traced back to Larry Shaw, a physicist who is believed to have held the first ever Pi Day celebration in 1988. 

  Although the day has nothing to do with food, revellers have been known to cook up a pie or two to mark the celebration.These are often decorated with the mathematical symbol π.

  圆周率（Pi）是圆的周长与直径的比值，一般用希腊字母π表示，是数学和物理学中普遍存在的数学常数，通常缩写为3.14159。1988年，物理学家拉里·肖(Larry Shaw)首次提出庆祝圆周率日(Pi Day)。2011年，国际数学协会正式宣布，将每年的3月14日设为国际圆周率日，也称作国际数学节。尽管除读音相同以外，Pi与Pie(派，一种食物)并无联系。人们还是乐于在圆周率日这一天烹制一块派，在上面摆上π的标志。

  圆周率日是哪一天？

  Every year, Pi Day is observed on March 14. The event falls on this specific date because the first three significant digits of π are 3, 1 and 4. In 2009, the US House of Representatives officially recognised the date as a national celebration. As well as honouring pi, the celebration works to inspire further academic research and interest in maths and science.

  每年的圆周率日都是3月14日，因为π的前三个数字是3、1和4。2009年，美国众议院认定圆周率日为国家节日。除了纪念π这个符号以外，圆周率日也旨在激发对学术研究以及数学和科学的兴趣。

  Why do we celebrate Pi Day?

  为什么庆祝圆周率日？

  As the exact digits of the irrational number remain unknown, the mystery of π has continued to enthral academics. The special constant shows up across many disciplines, including chemistry, physics and maths. Although the official premise of the day is to honour π, many believe it’s more of a celebration of academia. For this reason, schools, universities and museums across the globe encourage festivities.

  由于π这个无理数的确切位数仍然未知，它的神秘性一直吸引着学者。这个 特殊常数出现在化学、物理和数学等多个领域。 尽管这一天的官方前提是庆祝π，很多人认为这一天更是对学术界的庆祝。 全球各地的学校、大学和博物馆都鼓励相关庆祝活动。

  关于π的有趣事实

  1. It’s the 16th letter of the Greek alphabet

  2. It was proved to be an irrational number in the 18th Century

  3. There are no occurrences of the sequence 123456 in the first million digits of pi

  4. The World Record for memorising the digits of pi belongs to Lu Chao, from China. The maths whizz was able to recall the first 67,890 numbers

  5. Using a powerful computer, the Hitachi SR 8000, a Japanese scientist found 1.24 trillion digits of Pi, breaking all the previous records

  6. Pi Day falls on March 14, which is German genius Albert Einstein’s birthday

  7. Pi has featured in many a Hollywood blockbuster, as it was used as the secret code in Hitchcock’s Torn Curtain and also in The Net, which stars Sandra Bullock

  1. 它是希腊字母表中的第16个字母。

  2. 18世纪，π被证明是一个无理数。

  3. π的前100个数字中，没有连续出现过123456。

  4. 官方记录显示，能记住π最多位数的是中国的吕超，他能记住前67890位数。

  5. 日本数学家通过性能强大的日立SR 8000电脑，算出π的前1.24兆亿位数，创造了新的记录。

  6. 圆周率日是3月14日，这一天也是德国天才爱因斯坦的生日。

  7. 很多好莱坞大片中都把π当做秘密代码，例如希区柯克的《冲破铁幕》和桑德拉·布洛克主演的《网络上身 》。

  现在，π你还能背到多少位？

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