Taylor Swift
"Bad Blood" singer Taylor Swift, a contrarian, considers the No. 13 lucky. She is pictured at the Victoria's Secret Fashion Show Nov. 13, 2013. Getty Images

Great ready, believers of superstition: The third and final Friday the 13th of 2015 is here. While many people believe it’s an unlucky day, a belief that supposedly goes back to Biblical times, the No. 13 is considered lucky by some. To find out more about Friday the 13th and its foreboding reputation for misfortune and bad luck, continue reading some facts listed below, courtesy of Live Science, History.com and How Stuff Works.

1.Friggatriskaidekaphobia is the fear of Friday the 13th. Almost 20 million Americans have friggatriskaidekaphobia, which is also called paraskavedekatriaphobia. Those who don’t mind Friday, but fear the No. 13, have triskaidekaphobia.

2. Since there’s such a fear of the No. 13 among Americans, there are many infrastructures that leave off that number. For instance, many hospitals don’t have a room number with 13 in it, and there is usually not a 13th floor. In tall buildings the 13th floor is typically skipped and some airlines do not have a Gate 13.

3. There can be more than one Friday the 13th a year. In 2015, there were three, which is the most that can occur. There is at least one Friday the 13th per year.

4. The No. 13 is considered lucky by Italians. It’s also popular with “Bad Blood” singer Taylor Swift. She paints the digit on her hand before every show. "My first No. 1 song had a 13-second intro, and every time I win an award I'm always seated in either the 13th seat, 13th row or the 13th section," she told E! Online in 2009.

5. Where there is fear, there is profit: Hollywood has created 12 “Friday the 13th” movies. Four of them were released on the spooky day.

6. Thirteen supersedes 12, a number of “completeness,” which is one of the reasons the credulous don’t like it. For example, there are 12 months in a year, 12 hours in a clock, 12 eggs in a dozen, 12 Zodiac Signs, 12 Apostles of Jesus, 12 Gods of Olympus, 12 tribes of Israel, 12 days of Christmas and 12 labors of Hercules.

7. A 13th guest at a table is considered bad luck. In Paris, sometimes a “quatorzieme” is hired to act as a 14th guest. Instead of asking someone to leave, a professional will be added to balance out the luck.

8. Following with the table superstition, President Franklin D. Roosevelt would never have a 13th guest at a meal. He also would not travel on the 13th, no matter the day of the week it fell on.

9. Fidel Castro was born Friday, Aug. 13, 1956.

10. Tupac Shakur was killed Friday, Sept. 13, 1996.

11. Butch Cassidy, infamous American train and bank robber, was born Friday, April 13, 1866.

12. Former NFL Miami Dolphins quarterback Dan Marino, who is regarded as a quarterback great, wore the No. 13 on his jersey.

13. It’s not just the No. 13 that gets a bad rap. Friday has a longstanding stigma in the Christian faith. Jesus was notoriously crucified on a Friday, the flood with Noah’s ark began on a Friday and the story about the original sin of Adam and Eve occurred on a Friday.

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