The check digit is used to confirm the initial digits of the card number. The benefits of using a checksum is that it prevents casual attempts to invent credit card numbers, as only one in ten will be valid.
Length (adj). the longest, or longer, dimension of any object, in distinction from breadth or width; extent of anything from end to end; the longest line which can be drawn through a body, parallel to its sides; as, the length of a church, or of a ship; the length of a rope or line.
What is the longest snake ever recorded? The longest snake ever recorded was a 11.5 meter green anaconda from South America (Oliver 1958 and Gilmore and Murphy 1993). Some biologists dispute this and consider the maximum length to be only 9 to 9.5 meters.