For the geeks and number-heads out there, it doesn’t get much better than this.

Friday is Odd Day, a day whose date written in the US style - 11/13/15 - has three consecutive odd numbers.

No big deal, you might say, until you learn it is the last day of its kind this century.

Indeed, sequential odd days only ocurr six times in a century and this is the last one for the 21st. The next one will not come around for

90 years, when January 3, 2105 rolls around. That date will be 1/3/5.

The San Francisco Chronicle reported that a former Redwood City high school teacher monitors Odd Day, along with other mathematically odd days including Square Root Day (4/4/16), All Ones Day (1/1/11) and Trumpet Day (2/2/22, or toot-toot-toot-too).

Ron Gordon, who is the guardian and semiofficial keeper of such days, offers prizes to people who people who write poems, draw pictures or do something else to give such a meaningful occasion its due.