The fear of number 13 is called triskaidekaphobia and it was derived from the word treiskaideka, the Greek word for thirteen and phobia. There were thirteen people at Christ’s Last Supper before his captivity. He was betrayed by thirteenth guest. Maybe this is how everything started. Routine mission to the moon goes drastically wrong on Apollo 13. Some hotels skip number thirteen when numbering rooms. In Formula 1, there is no car with the number 13. Alfred Hitchcock was born on 13-August-1899 and tried to make movie about this number, but failed due to financial reasons. Who really started this calamity? I guess we will never find out, but it exists and for some people it is a serious obstacle. In many cases people will remember if something bad happens on Friday the 13th while forgetting other days. Maybe number 13 is not as cool as number 12. There are 12 Gods, 12 Apostles, 12 months, 12 eggs, 12 tribes of Israel , 12 Zodiacs etc. Humans have need to separate bad from good so they do it with numbers. Record every time when something good happens on number 13 and you will be surprised with results. Pagans believed that thirteen is the lucky number because there are 13 full months in the year.