Question

12. Everybody in a room shakes hands with
everybody else. If there are 12 persons in th
room, then total number of hand shakes is
1) 66 2) 60 3) 56 4) 50​

Answer 1

Answer:

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

Answer is 12. I want to know the method.

Pls answer only if you know the method.

Answer 2

Answer:

But if (1) shakes hands with (2), there is no need for (2) to shake hands with (1), so the number is halved. 20 / 2 = 10 handshakes (for 5 people). This gives the general formula: So for 12 people that's 66 handshakes.

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