Riddle

There are one hundred people at a party. Everybody shakes hands with everybody else. How many handshakes are there?

This is quite straightforward and is not a trick question. I have a theory about what kind of person will answer this without difficulty and what kind of person will struggle with it or get it wrong. It is not a matter of intelligence.

Write down your answer, put it in a sealed envelope and leave it in the hands of someone of the utmost integrity, if you know such a person. Then, and only then, go here.