There is a Biblical reference to the “unlucky” number 13. Judas, the apostle who betrayed Jesus, was the 13th guest to the Last Supper. Also, in ancient Rome, witches reportedly gathered in groups of 12. The 13th was believed to be the devil. Some people also point to the ill-fated mission to the moon, Apollo 13.

Numerologists consider 12 a “complete” number. There are 12 months in a year, 12 zodiac signs, 12 gods of Olympus, 12 labours of Hercules, 12 tribes of Israel, and 12 apostles of Jesus. In exceeding 12 by 1, the number 13 becomes “restless or squirmy”.

As for Friday, it was the day of crucifixion of Jesus. Biblical scholars also believe that Eve tempted Adam with the forbidden fruit on a Friday. There is also a belief that Abel was slain by Cain on Friday the 13th.