Pi Day is on March 14. This is the day when mathematicians（数学家） and geometry（几何学） enthusiasts（爱好者） around the world get together and celebrate the mathematical constant（常数） of Pi.There are two good reasons to hold Pi Day on March 14. The first is that in the American date format（格式）, it is 3/14 and Pi, to two decimal （小数的）places, is 3.14. The other reason is that March 14 is Albert Einstein’s birthday, and he knew a thing or two about numbers.Pi Day started in 1988 at the San Francisco Exploratorium. The museum staff walked around the circular（圆形的） spaces in the building eating fruit pies. Cherry and apple pies have very little to do with Pi, unless you want to calculate（计算） the circumference（圆周） of your fruity treat.Pi is a letter of the Greek alphabet. The symbol was first used in mathematical calculations in 1737 by the Swiss mathematician Leonhard Euler. It is used for the ratio（比率） of the circumference of a circle to its diameter（直径）.Computers have calculated Pi to over one trillion digits. It has countless numbers of digits. Perhaps more impressive（令人惊叹的） is the feat（技能） of British autism（自闭症） sufferer Daniel Tammet. He holds the European record for reciting Pi from memory to 22,514 digits in just over five hours. He also suffers from a condition in which he sees numbers as colours. He says Pi is particularly beautiful.The worlds of science, engineering and mathematics would be lost without it. Celebrate today with your favourite pie!
圆周率日是3月14日。在这一天，世界各地的数学家和几何学爱好者聚在一起，庆祝圆周率的这一数学常数。在3月14日举行圆周率日有两个很好的理由。第一个是在美国日期格式（格式）中，它是3/14，而π保留两位小数后，是3.14。另一个原因是，3月14日是阿尔伯特·爱因斯坦的生日，他对数字有自己的见解。圆周率日始于1988年的旧金山探索博物馆。博物馆的工作人员在大楼里的圆形空间里四处走动，吃着水果派。樱桃派和苹果派与圆周率没有什么关系，除非你想计算你手里的水果派的周长。计算机计算出的圆周率已经超过了1万亿位数。它有无数个的数字。也许更令人印象深刻的是是英国自闭症患者丹尼尔·塔米特的壮举。他保持着在5个多小时内从记忆中背诵圆周率到22,514位的欧洲纪录。他还患有一种以他视数字为颜色的疾病。他说 π 特别漂亮。如果没有π，科学、工程和数学的世界就会消失。今天就用你最喜欢的馅饼（pie）来庆祝吧！
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