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. unofficial holidaysquare rootdigits

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, Square Root Days fall upon the same nine dates each century.

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

Gordon remains the holiday's publicist, sending news releases to world media outlets. Gordon's daughter set up a Facebook group where people can share how they were celebrating the day.publicistnews releasesmediaFacebook

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")squareradishesroot vegetablescross sections

 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

Pi Day is a holiday commemorating the mathematical constant π (pi). Pi Day is celebrated on March 14 (or 3/14 in month/day date format), since 3, 1 and 4 are the three most significant digits of π in the decimal form. In 2009, the United States House of Representatives supported the designation of Pi Day.holidaymathematical constantπ (pi)March 14date formatsignificant digitsUnited StatesHouse of Representatives