# handshakes = n*(n - 1)/2. This is because each of the n people can shake hands with n - 1 people (they would not shake their own hand), and the handshake between two people is not counted twice. This formula can be used for any number of people.

How many handshakes if there are 5 people?

If two people shake hands there is one handshake. If three people shake hands there are 3 handshakes. If four people shake hands there are 3 more handshakes so 3 + 3 = 6 in total. If five people shake hands there are another 4 handshakes so 6 + 4 = 10.

What is handshake problem?

people at a party. Not being able to shake hands with yourself, and not counting multiple handshakes with the same person, the problem is to show that there will always be two people at the party, who have shaken hands the same number of times.