There are 40 people in a party. If everyone is to shake hands with one another, how many hand shakes are possible?
Options
A) 780
B) 667
C) 661
D) 297
E) 261
Explanation:   Total number of persons = n = 40   Shake hands involve only 2 persons = r = 2   Number of shake hands = nCr = 40C2   40C2 = (40 * 39) /(2 * 1)= 
<gadget id="calculator">(40 * 39) /(2 * 1)</gadget>
<output>780</output>
780   780NSWER:780
<result>A</result>
There are 40 people in a party. If everyone is to shake hands with one another, how many hand shakes are possible?