Suppose that 4 cards are drawn from a well shuffled deck of 52 cards. What is the probability that all 4 are clubs?

Another way of looking at this is as follows:

Probability that the 1st card is a club = 13/52

Probability that the 2nd card is a club, given the 1st is a club is: 12/51

Probability that the 3rd card is a club, given the first 2 are clubs is:  11/50

Probability that the 4th card is a club, given the first 3 are clubs is:  10/49

Hence the overall probability that all four are clubs is the product of these = 13*12*11*10/(52*51*50*49)

This can be written as (13!/9!)/(52!/48!)  = (13!/[9!*4!])/(52!/[48!*4!]) = nCr(13,4)/nCr(52,4)  (or C(13,4)/C(52,4) using Chris's notation).

There are 13 clubs, and we want to choose any 4  = C (13 , 4)

And the number of possible way to choose any 4 of 52 cards in the deck  = C(52 , 4)

Calculate both and divide the first thing by the second.....and that will be your decimal answer........