Following the third, fourth, or fifth digit, every number up through 15 is the account number while that final number, 16, is the check digit. All Discover cards start with the number six and are 16 digits in length, while petroleum cards start with the number seven and airline cards start with the number one.
Vatican City. Vatican City â 0.2 square miles â The worldâs smallest state, the Vatican has a population of 770, none of whom are permanent residents. The tiny country which surrounds St. Peterâs Basilica is the spiritual center for the worldâs Roman Catholics (over 1 billion strong).
Smallest Countries in the World. By contrast, the total population of the world's smallest countries is only just under 300,000. The smallest country in the world in 2016 is Vatican City, the small enclave within the Italian city of Rome that is ruled by the Pope and home to just over 800 people.