say your sence organs are 7, days in week are 7, no of continents 7, no of oceans 7, layers on atmosphere 7, color in rainbow 7or primary colors 7. in Hindu marriage ceremony the take 7 rounds around the fire to complete the marriage, Layers in earth till core is 7, Maximum no of rebirth a person can take is 7, in meditation there are 7 ‘Chakras’ if you attain 7th level or chakra you gain enlightment, and you can find manymore such examples in every culture say Hindu or Muslims or Sikh or christan, I know some more from Hinduism, but you all can also start wondering why everything ends at 7
