Permutation is an ordered arrangement of a group of objects. 1  The permutation of n objects taken r at a time is represented as nPr. 2  The permutation or arrangement of 9 different balls in 3 different rows can be done in 9P3 = 504 ways.  The permutation of n objects taken all at a time is represented as nPn = n!.
Collagen is a protein that is part of cartilage, bone, and other tissues in animals and humans. People use collagen from chickens for medicine. Chicken collagen is used to treat joint pain associated with many types of arthritis and surgery, as well as back pain, neck pain, and pain following injury.
Collagen occurs throughout the body, but especially in the skin, bones, and connective tissues. Some types of collagen fibrils, gram-for-gram, are stronger than steel. Collagen production declines with age and exposure to factors such as smoking and UV light. Collagen can be used in collagen dressings, to attract new skin cells to wound sites. Cosmetic lotions that claim to increase collagen levels are unlikely to do so, as collagen molecules are too large to be absorbed through the skin.