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).
Monaco is the world's second smallest country and is located between southeastern France and the Mediterranean Sea. Monaco is only 0.77 square miles in area. The country has only one official city, Monte Carlo, which is its capital and is famous as being a resort area for some of the world's richest people.auru is the world's smallest island country at an area of just 8.5 square miles (22 sq km). Nauru had a 2011 population estimate of 9,322 people. The country is known for its prosperous phosphate mining operations in the early 20th century.