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.
Shridhar Chillal. Shridhar Chillal (born 1938) holds the world record for the longest fingernails ever reached on a single hand, with a combined length of 909.6 centimeters (358.1 inches). Chillal's longest single nail is his thumbnail, measuring 197.8 centimeters (77.87 inches). He stopped cutting his nails in 1952.