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.
TL = 0.22 + 0.058(CD) Where TL is the total length of the shark in meters, and CD is the diameter of the largest vertebra centurm in mm. The second vertebra method comes from Shimada (Shimada K, 2008). In 2008 he estimated the body length of Cretoxyrhina mantelli, a cretaceous shark.