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.
Some also use length in the same context as distance like when one says, âHold it at armâs length!â. Summary: 1.Length is describing how long something is while width is describing how wide an object is. 2.In geometry, length pertains to the longest side of the rectangle while width is the shorter side. 3.Length can also refer to an extent of time or a measure of distance. 4.The most common unit for measuring length is the meter.