If 4 numbers from 1 to 1000 are chosen at random, one at a time, find the probability that they will be chosen in increasing order.
If we choose any four numbers from the first thousand integers, we will have
C(1000, 4) different sets of four numbers
And each can be arranged in 4! ways = 24 ways
But only one arrangement of each of these sets is in the desired order
So....the probability of the correct arrangement is just 1 / 24