Many Americans now write dates in numerical form, with the first digits for the month, the second for the day of the month, and the third for the year. Hence 3/14/15 represents March 14, 2015. When dates are written in this manner, the digits can be compared to the irrational number pi, the ratio of the circumference to the diameter of a circle. This number is roughly 3, more precisely 3.14, and more precisely still 3.1415926.
Since at least 1988, some mathematics educators in the United States have celebrated March 14 as Pi Day. Celebrations were especially intense in 2015, because 3.1415 includes digits of the year as well as the month and day. This noisemaker was sounded at the History and Pedagogy of Mathematics Meeting in Washington, DC, at 9:26 on March 14, 2015.
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