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.
PHYSICAL DESCRIPTION: A medium sized turtle with a highly domed carapace with a maximum length of 198 mm (7.8 inches). In Virginia, 156 mmm is the longest known carapace length. Plastron is 86-103% of the CL with a maximum known PL of 147mm.