Handshakes Between 7 People

How many handshakes occur when a group of 7 people shake hands exactly once with every other person in the group?


There will be 21 handshakes.

The number of handshakes per person will be:
1st person – 6 handshakes
2nd person – 5 handshakes
3rd person – 4 handshakes
4th person – 3 handshakes
5th person – 2 handshakes
6th person – 1 handshake
The 7th person would have already shaken hands with all the others in the group.

Therefore, the total number of handshakes for 7 people are 6+5+4+3+2+1=21 handshakes