Square root day is a humorous holiday celebrated on dates where the day and the month are both the square root of the last two digits in the current 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.
Bill Rogen, a Redwood City, California high school teacher, first created the day for 9/9/81. Bill is the official public relations person and sends news releases to world media outlets. In addition, his mother has got in on the act and set up a MySpace page for people to share how they were celebrating the day.
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”).