Advance Functions

Question

Ten teachers met at a mathematics conference. Each teacher shook the hand of each of the other teachers exactly once. How many handshakes were there?

Answer 1

Imagine the teachers in a line:

The first teacher shakes 9 others and leaves.

The second teacher shakes 8 other and leaves.

The third teacher shakes 7 hands and leaves.

 

Can you continue the pattern and answer the question?