We have 53 ways to pick the first number, 52 ways to pick the second, 51 ways to pick the third, etc. =
53 x 52 x 51 x 50 x 49 x 48 = 16,529,385,600 combinations
But, we need to divide this by 6! = 720 because the set [21, 33, 2, 5, 19, 6], for example, has 720 different arrangements
So .. 16,529,385,600 . 720 = 22, 957, 480
Note that this is exactly the same as C(53, 6)......!!!