A Puzzle

The Wednesday song will be posted in a little while. For now, a Wednesday puzzle. (This will not be a weekly feature.) Here's the question:

At a party with 100 guests, everyone shakes hands with everyone else. How many handshakes take place?

The answer can be found at the bottom of this column. I'm happy to say that I got it right, though of course I have no way of proving that.

(Via Norm Geras)