Counting people from handshakes

At a gathering everyone shook hands with everyone else exactly once, totaling 6666 handshakes. How many people were there?

Show hints (2)+
  1. Handshakes $= \binom{n}{2}$.
  2. Solve $n(n-1) = 132$.

Answer

Reveal answer →

12

Want the full step-by-step worked solution? It's part of Premium — along with a worked solution for every question in the bank.

Asked at: Optiver, IMC

Related questions