Square Root Day!
Today is Square Root Day, when the day and the month are both the square root of the last two digits of the current year. So March 3, 2009 = 3/3/09, or √9 = 3, or 3² = 3 × 3 = 9.
I always love numbers; love telling people how my birth date is actually easier to remember when you take the last 2 digits of the year I was born, divided by 3 to get the date and then divided the result by 4 to get the month. I thought it was amusing, while the person I told it to just looked at me funny.
More fun mathematically-related day to come: 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.