Ron Gordon, the California teacher who founded and promoted Square Root Day reminds us that Thursday is another math holiday, Odd Day! The calendar date (as written by people in the US) will be 5-7-9, which only happens once a century. Odd Days happen six times a century. It's a day to take the opportunity to do something odd. In celebration, there's another contest, with $579 up for prizes. Get all the details at the Odd Day website. Link -Thanks, Ron!