It is Friday, the 13th. And many people are superstitious about this day. There actually is a name for the fear of the number 13 - Triskaidekaphobia.
So, why does the number 13 give people such a bad case of the heebie-jeebies? There are many stories surrounding it....
At the Last Supper in Christian theology, there were 13 dinner guests, so that number is unlucky because Christ was betrayed.
And when a group of 13 objects or persons is divided into two, three, four or six equal groups, there is always one leftover, "unlucky" object or person.
Some more interesting 13 facts:
President Franklin D. Roosevelt was very fearful of the number 13. If it ever looked as if there might be 13 people at an event, he invited his secretary to join them so there wouldn't be 13. This is because legend has it: If 13 people sit down to dinner together, one will die within the year.
And finally - If you have 13 letters in your name, many believe you will have the devil's luck. Jack the Ripper, Charles Manson, Jeffrey Dahmer, and Theodore Bundy all have 13 letters in their names.