The hip is a ball-and-socket joint. The socket is formed by the acetabulum, which is part of the large pelvis bone.The ball is the femoral head, which is the upper end of the femur (thighbone).he hip is a ball-and-socket joint. The socket is formed by the acetabulum, which is part of the large pelvis bone.
Most of us carry credit cards and ATM cards. These, typically, have sixteen digits on the front. These digits are the unique account number for the card. For obvious reasons, just any sixteen digits will not work, they follow pattern. The first few characters of the card number describe the type of card.
To try and minimize this, credit card numbers contain a check digit. In a typical sixteen digit credit card number, the first fifteen digits are determined by the issuing bank, but the last digit, called the check digit, is mathematically determined based on all the other digits.