Square Root Day

有位印度人在本宅犬的新twitter告知「happy square root day」。

國內都沒人寫關於Square Root Day的事，只好google一下。

Square Root Day is an unofficial holiday celebrated on days when both the day of the month and the month are the square root of the last two digits of the year. For example, the last Square Root Day was March 3, 2009 (3/3/09), and the next Square Root Day will be April 4, 2016 (4/4/16). The final Square Root Day of the century will occur on September 9, 2081. Square Root Days fall upon the same nine dates each century. The exceptions during this millennium are during the 21st century with the 10/10/2100 day and 22nd century with the 11/11/2121 and 12/12/2144 days also being the Square Root Days.

Ron Gordon, a Redwood City, California high school teacher, created the first Square Root Day for September 9, 1981 (9/9/81).

One suggested way of celebrating the holiday is by eating square radishes, or other root vegetables cut into shapes with square cross sections (thus creating a "square root").

Full list of Square Root Days
．1/1/01　．2/2/04　．3/3/09
．4/4/16　．5/5/25　．6/6/36
．7/7/49　．8/8/64　．9/9/81

[by wiki]


The last Square Root Day was five years ago on Feb. 2, 2004, which coincided with Groundhog Day.

The next is seven years away, on April 4, 2016.