assume those 4 kings in the packs of 52 cards as 1 card (because we want to fetch all king cards), so in that way there is only 49 cards. Now there is only 1 favourable condition to fetch 4 kings ,so probability of fetching 4 kings is=1/49,now we want to fetch any of the two cards from 49 cards(remember we are fetching 6 cards at onece not like fetching the kings first and then 2 cards) so the probability is =48/49.

final probability is =(1/49)*(48/49)=0.01999167 is your answer.