Throughout the course of history, the number 13 has always been associated with bad luck and misfortune to whoever decides to go out and test his/her fate during the 13th of the month associated with a Friday.
For example, despite the absence of scientific evidence to prove the superstitions, a lot of architects still omit the 13th floor in their building designs and go straight to the 14th floor after the 12th, as if that will change anything about the real floow number of the 14th floor. Then a number of firms, such as the US Navy, even avoid to launch ships during Friday the 13th. Sometimes it's bizarre that the supposed unluckiness of the number 13 has crept its way up to this very day.
I am actually not surprised why millions of people around the world actually have this kind of phobia, which is specifically called Triskaidekaphobia.
In numerology, however, the number 13 has its fair share of good and bad qualities. The number is represented by laziness, immaturity, and idleness. But it also represents strong loving emotions, making it just as regular any other number out there. Bad luck associated with Friday the 13th is just a misconception misconstrued by people of the old times.
A number of theories try to explain the origin of the myth, though there are no sufficient convincing evidence describing the myth's origin. In my opinion, the most popular origin of the Firday the 13th is that it was on October 13, 1307, when King Philippe IV of France ordered a pre-dawn raid of the Knights Templar.
We really cannot be sure. It could be the Knights Templar scenario, some other scenario, or just probably a random idea that someone had come up with many years ago. We really cannot tell. What's sure is that the misconception about the number will remain, though it will just remain like that. A misconception. Now we should go on with our respective lives and think of 13 just like every number out there and not some product of some medieval raid.