There are 6 people in aroom each of them shakes hand exactly once with one another how many hand shakes tre there

Ans:
In arithmetic progression/sequence, to calculate the number of handshakes you could use this equation: n(n-1)/2.

The variable n is the number of people in the room, which is six people, inputing the number 6 in n results in this equation:
Sn=n.(n-1)/2
S6=6.(6-1)/2
S6=6.5/2
S6=30/2
S6=15 

Using the equation above, you would find that the number of handshakes that occur in the room is 15 handshakes.