Everybody in a room shake hands with everybody else. If the total number of handshakes is 66, then the number of persons in the room is-

Everybody in a room shakes hands with everybody else. If the total number of hand shakes is 66, then the total number of persons in the room is

Everybody in a room shakes hand with everybody else. The total number of handshakes is 66. The total number of persons in the room is :

Everybody in a room shakes hands with everybody else. The total number of handshakes is 45. The total number of persons in the room is

Every body in a room shakes hands with everybody else. The total number of handshakes is 21. The total number of persons in the room is

Every body in a room shakes hands with every body else. The total number of hand shakes is 66. The total number of persons in the room is