Subscribe | UPI Odd Newsletter Subscribe REDWOOD CITY, Calif., Jan. 3 (UPI) -- Monday has been declared an official holiday for oddballs who appreciate the date contains the first three odd numbers, the New York Daily News reported. In U.S. date format, 1/3/05 happens only once a century, the last time being Jan. 3, 1905. That's enough to prompt a Redwood City, Calif., safety teacher to declare the day a holiday. Advertisement "Halley's Comet happens more frequently than this does," said Ron Gordon. The 59-year-old has a soft spot for calendar quirks, as evidenced by his declaration of Square Root Day on 9/9/81. He suggested in observation of Monday's "oddness," people do mental gymnastics to determine why adding odd numbers always results in a positive sum.