In a room there are 11 people. Each person shook hands with every other person. How many hand shakes were there? Choose one: A) 52 B) 53 C) 54 D) 55 E) 56
11C2 = 55   The answer is 55.
<result>D</result>
In a room there are 11 people. Each person shook hands with every other person. How many hand shakes were there?