If the thought of Friday the 13th sends shivers down your spine, don’t worry. You’re not alone.

The fear of Friday the 13th, or just the number 13, is a common one. So common there’s a name for it.

Why has the number come to be seen as unlucky? There is a rather unnerving tally of historical events that have led to the misfortune under which the number 13 suffers.

Here are a few of them:

When it was unlucky

• Pope John Paul II was shot and nearly died on May 13, 1981.
• There were 13 people at the Last Supper, and it is believed that Judas Iscariot — the disciple who betrayed Jesus Christ — was the 13th man to take his place at the table.
• Jesus Christ was crucified on a Friday.
• A 13-year-old boy in England was struck by lightning on Friday the 13th at 1:13 p.m. (in military time, 13:13).
• On Oct. 13, 1307, there was a mass arrest and execution of members of the Knights Templar. The Knights Templar or the Poor Fellow-Soldiers of Christ were anything but. Members were among the wealthiest and most powerful of Christian military orders. They are credited by many with establishing one of the earliest financial systems.
• In not-so-Jolly Ol’ England, Friday was the traditional day for public hangings. Insult to injury — there were 13 steps up to the gallows, generally.

When it was lucky

• The number 13 bus in London was never damaged during the blitz of the Second World War.
• Apollo 13 was a 1970 NASA Moon mission famous for being a “successful failure.” The accident that crippled the spacecraft happened on April 13.
• It was on the jersey of Miami Dolphins Hall of Famer Dan Marino.
• It was on the jersey of Los Angeles Lakers and Philadelphia 76ers Hall of Famer Wilt Chamberlain.
• A baker’s dozen means you get 13 of something — or one more than a standard dozen. The downside is it is sometimes called a “Devil’s dozen” (think donuts).
• The visions of the Virgin of Fátima were said to have appeared on the 13th day of every month for six months in 1917.
• It is singer Taylor Swift’s lucky number.

Where 13 is not used

• There is no 13th floor in many high-rise buildings.
• There is often no 13th floor in hospitals, and airports generally don’t have a Gate 13.
• In triathlons, the number 13 is not used.
• The number was not used in Formula One racing from 1977 to 2013.
• While there are 19 counties in Norway they are numbered 1-20 because there is no number 13 county.

13 in general

• Aluminum has the atomic number 13.
• Thirteen is the sixth prime number.
• It is the smallest emirp or a prime number that is a different prime when it’s reversed - 31.
• Fear of the number 13 is called triskaidekaphobia.
• Fear of Friday the 13th is paraskevidekatriaphobia or, sometimes, friggatriskaidekaphobia.
• Fear of the number 17 – the number of letters in triskaidekaphobia – is heptadecaphobia.
• The Aztecs considered 13 a sacred number. It was the number that represented time. It stood for completion.
• In Tarot, 13 is the card of “death.” The card stands for transformation — ending something and starting something new.
• There are 13 stripes on the American flag.
• There are 13 stars in the Great Seal of the United States.

Cox Media Group