6 people meet for a business breakfast. Each person shakes hands once with each other person present. How many handshakes take place?  Answers.
A) 30 B) 21 C) 18 D) 15 E) 10
Let's look at the logic.   Every person shakes hand with other '5'. So, 6 people shake hands with 6X5= 30 people   But in this 30 we have counted two times the total handshakes (c shakes hand with d and d shakes hand with c)   So just divide 30/2= 
<gadget id="calculator">30/2</gadget>
<output>15</output>
15 total handshakes   Answer is 15
<result>D</result>
6 people meet for a business breakfast. Each person shakes hands once with each other person present. How many handshakes take place?