Question

maths
permutation and combination

Answer 1

If the order doesn't matter then we have a combination, if the order do matter then we have a permutation. One could say that a permutation is an ordered combination. The number of permutations of n objects taken r at a time is determined by the following formula: P ( n , r ) = n ! ( n − r ) !

Answer 2

permutations is an arrangement in a definite order of a number of objects taken some all at a time.
combination each of the different groups or selection that can be made out of a given number of things by taking some or all of them at a time irrespective of their arrangements is called a combination.