6 chess players take part in a tournament. Every player plays twice with each of his opponents. How many games are to be played? Choose one
A) 19  B) 20  C) 30  D) 33  E) 34
Though 2*(6C2) is the correct approcah to do this, but for people like me who find Perm, Comb n Prob a nightmare, an easy approach can be used.   The first guy has to play 2 matches with the rest of 5, so he'll play 10 matches.   Similarly, second guy has to play with the rest of 4 as his 2 games with the first guy are already played. So he plays 8matches.   This continues like this and the total matches are 10+8+6...+2   10+8+...+2 = 2(5+4+...+1) = 2((5*6)/2) = 5*6= 
<gadget id="calculator">5*6</gadget>
<output>30</output>
30.   ANSWER:30
<result>C</result>
6 chess players take part in a tournament. Every player plays twice with each of his opponents. How many games are to be played?