What's the difference between these two: 1) The number of permutations of n distinct objects taken r at a time is and 2) The number of combinations of n distinct objects taken r at a time is ?
You have surely already noticed that: since permutations = and combinations = then combinations = permutations time hgmjr
Can you be more specific as to what you are trying to understand. The literal answer to your question is that the difference is Surely, that is not what you mean. Are you trying to undrstand what the definitions of permutations and combinations are?
permutations - order does matter in counting ABC is different then BCA combinations - order doesn't matter if you have to choose 2 elements out of 5 elements. Example {A,B,C,D,E} you don't count {A,B,C} different from {B,A,C} They are the same But permutations would consider them both different and count as 2 .
To support Mathematics! combinations = "select" Ex: In how many ways you can select 3 letters from A,B,C,D,E? 5!/(3!2!) permutations = "select and arrange" Ex: In how many ways you can select 3 letters from A,B,C,D,E and then arrange those 3 letters? 5!3!/(3!2!) = 5!/2!
Permutation is usually understood to be a sequence containing each element from a finite set once.. Combination is arrangment of elements in any order, to get different possible sequences