You can put this solution on YOUR website! This would be a combination of 100 items taken 2 at at time. It turns out that choosing 98 out of 100 is exactly the same, 4950.
Think of the situation in which you are choosing 2 delegates out of 100 members of a club to attend a conference. When you choose the 2 delegates to GO, you are automatically choosing the 98 members who will NOT GO!! Choosing 2 to GO is the same as choosing the 98 who will stay behind.