The maximum length of the number of a credit card can be 19 digits, and the length of the account field can maximum be 12 digits. Each issuer can have a trillion possible numbers of an account. The final digit on a credit card number is a check one, similar to a checksum. It confirms the initial digits of the number and prevents the attempts to invent card numbers.
Longest lasting empire in history. The Roman Empire is considered to have been the most enduring in history. The formal start date of the empire remains the subject of debate, but most historians agree that the clock began ticking in 27 BC, when the Roman politician Octavian overthrew the Roman Republic to become Emperor Augustus.
Longest Reigning European Monarchs. The above list includes only rulers of empires and kingdoms. Afonso I of Portugal (1109-1185) reigned as Count of Portugal from 1112, and as King from 1139. Prince Johann II of Liechtenstein reigned 71 years (1858-1929). His was the longest reign of any sovereign in history that did not require a regency as he was already 18 at his accession. Friedrich August III (I) of Saxony reigned for over 63 years (1763-1827), from 1763 to 1806 as Elector and from 1805 to his death as King.