[MortalWombatDotCom]

i just composed a very nice post on how to calculate this, including the usual disclaimer that gaming mouse would come along in a couple of hours and explain the easy way, and right as i was finishing up the formatting bits (in fact, when i was asking a formatting question) i went and hit CTRL-W which in my IDE highlights the current word but in my browser closes the window.

anyway, if you are facing k opponents and were dealt, say, two clubs, the chance that at least one opponent was also dealt two clubs is

.k . . 39! * 11! * 2^i *(50 - 2k)! * (k choose i)
SUM . . ----------------------------------
i=0 . . . .(39 - 2k + i)! * (11 - i)! * 50!

ignore the '.'s, they are just there to make the quotient look nicer. you can pull the constants out, of course, but this way made more sense if you read the original post to see the derivation.

i know you wanted %. if you can't plug in the numbers yourself and nobody else steps up, i'll probably be un-grumpy enough to do it tomorrow. stupid browser. for k=1 it's .045 or 4.5% that an opponent has clubs, and for k=2 it's .088 or 8.8% that at least one opponent has clubs.

i probably made a mistake which would have been easy for someone to point out in the original post but without the derivation they probably won't bother.