Square Root Day, 03/03/09: Math Geeks Honor the Squarest of Days

The unofficial holiday comes around but nine times a century, when the numbers of the calendar align so that the month and day are each equal to the square root of the year as expressed in two-digit form. (In today's case, 3/3/09, 3 is the square root of 9—in other words, 32 = 3 x 3 = 9.) Square root days arise in every year whose last two digits are a perfect square, or a number whose square root is a whole number: The last square root day was on February 2, 2004 (2/2/04), and the next occurrence will be on April 4, 2016 (4/4/16).

The math-buffs' holiday, which only occurs nine times each century, falls on Tuesday — 3/3/09 (for the mathematically challenged, three is the square root of nine).

"These days are like calendar comets, you wait and wait and wait for them, then they brighten up your day — and poof — they're gone," said Ron Gordon, a Redwood City teacher who started a contest meant to get people excited about the event.

The winner gets, of course, $339 for having the biggest Square Root Day event.

Gordon's daughter even set up a Facebook page — one of a half-dozen or so dedicated to the holiday — and hundreds of people had signed up with plans to celebrate in some way. Celebrations are as varied: Some cut root vegetables into squares, others make food in the shape of a square root symbol.

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.[1] 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.

Ron Gordon, a Redwood City, California high school teacher, created the first Square Root Day for September 9, 1981 (9/9/81). Gordon remains the holiday's publicist, sending news releases to world media outlets.[2] Gordon's daughter set up a Facebook where people can share how they were celebrating the day.[3]

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").