The other popular number tattoo is of the number thirteen (13). This is a seemingly weird tattoo choice because superstitious people consider the number thirteen to be unlucky (Fear of the number 13 is called triskaidekaphobia). Friday the 13th is an especially unlucky day and hotels often designate the 13th floor and room to be 12b, so as to avoid any unhappy guests. However, number thirteen tattoos are considered to be symbols of good luck.
