Permutations and Combinations
combinations - order does not matter
e.g. number of ways of selecting top 3 finishers in a race with 7 horses = 7C3
permutations - order matters
e.g. number of ways of selecting 1st, 2nd, 3rd place from race with 7 horses = 7P3
N.B. e.g. number of ways of all 7 horses finishing 1st-7th = n! -->= 7!