If there are 8 people at a party and every person shakes hands with everyone else at the party how many handshakes will there be?
There will be 28 handshakes.
If you ask each person how many handshakes they had they will
tell you 7 making 7 x 8 = 56 handshakes in all.
But every hand involves two people, so every handshake has been
counted twice, thus there are 56 / 2 = 28 handshakes in all.