# Square Root Day revelers to party like it's 3/3/09

The rare holiday occurs when the day and the month are both the square root of the last two digits of the current year.

Count on Tuesday's alignment of the calendar to add some excitement to the lives of at least a few math geeks.

Tuesday is Square Root Day, a rare holiday that occurs when the day and the month are both the square root of the last two digits of the current year. Numerically, March 3, 2009, can be expressed as 3/3/09, or mathematically as √9 = 3, or 3² = 3 × 3 = 9.

"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," Ron Gordon, a Redwood City, Calif., teacher who organized a contest intended to publicize the event, told the Associated Press. The prize, or course, is \$339.

Celebrants are expected to mark the occasion by cutting root vegetables into squares or preparing other foods in the shape of the square root symbol.

Square Root Day occurs only nine times in a century. The last one occurred on February 2, 2004, and the next will occur in seven years on April 4, 2016.

Square Root Day isn't the only humorous holiday celebrated in the math world.

Pi Day is observed each March 14 (3.14), while Pi Approximation Day falls on July 22 (roughly equal to 22/7). The first Pi Day was observed in 1988 by staff at the San Francisco Exploratorium, who walked around in circles.

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