There are 21 people in an orientation group. Each person shakes hands with every other person exactly once. How many handshakes are there in total?

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Solution

Its similar to selecting any two people out of 21 people which is given²¹C₂ = 21!/(2! 19!) = 21Ã—20/2 = 210
So there are total 210 handshakes.

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There are 21 people in an orientation group. Each person shakes hands with every other person exactly once. How many handshakes are there in total?

Its similar to selecting any two people out of 21 people which is given 21C2 = 21!/(2! 19!) = 21Ã—20/2 = 210So there are total 210 handshakes.

Its similar to selecting any two people out of 21 people which is given²¹C₂ = 21!/(2! 19!) = 21Ã—20/2 = 210
So there are total 210 handshakes.