Happy Square Root Day! It’s March 3, 2009, or 3/3/09, and three is the square root of nine. These days come around nine times every 100 years — all in a rush at the beginning of the new century, starting with 1/1/01 and 2/2/04, and picking up after today with 4/4/16, 5/5/25, 6/6/36, 7/7/49, 8/8/64 and 9/9/81.
The Numbers Guy has more.