10 chess players take part in a tournament. Every player plays twice with each of his opponents. How many games are to be played?	Choose the correct choice from the following
A) 90 B) 98 C) 35 D) 99 E) 80
Though 2*(10C2) 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 9, so he'll play 18 matches.   Similarly, second guy has to play with the rest of 8 as his 2 games with the first guy are already played. So he plays 16 matches.   This continues like this and the total matches are 18+16+14...+2   18+16+...+2 = 2(9+8+...+1) = 2((9*10)/2) = 9*10= 
<gadget id="calculator">9*10</gadget>
<output>90</output>
90.   90NSWER:90
<result>A</result>
10 chess players take part in a tournament. Every player plays twice with each of his opponents. How many games are to be played?