There is a 4/52 or 1/12 possibility that we pick a spade in the first try, 3/51 or 1/17 possibility that we get a spade in the second try (because we already picked one spade in the first try, we subtract that from the number of spades and cards remaining), 2/50 or 1/25 in the third try, and 1/49 in the last try.

To get the probability of getting 4 spades, we multiply all the 4 possibilities mentioned above. So

1/12*1/17*1/25*1/49 =1/249,900.

The possibility of getting four spades is 1/249900 or 0.0004 percent.