8 men entered a lounge simultaneously. If each person shook hands with the other, then find the total no. of hand shakes?

Question: 8 men entered a lounge simultaneously. If each person shook hands with the other, then find the total no. of hand shakes?

Solution:
Required no. of hand shakes = ⁸C₂
= 8!/2!(8 - 2)!
= 8!/2! · 6!
= 28