There are actually many superstitions and stories as to how the number 13 became unlucky in nature. One of the reasons why the number 13 became unlucky is due to the fact that there were 13 people present at the biblical story of the "last supper". Another reason or possible explination for the number 13's unlucky nature is due to a Norse legend. This legend stated that a god by the name of "Loki" crashed a big party within the banquet of the gods. There were 12 people present within this part, and Loki made the 13th member of the party. Loki was known as a very mean spirited god, and thus once he crashed this banquet, things certainly turned for the worse! Another possible reason/explination as to how the number 13 became unlucky is due to the famous story written by Agatha Christie called "The 13 Problems".