Five friends met and each shook hands with each other exactly once. How many handshakes were there in total?
Show hints
- Don't count the same handshake twice.
- Add 4, 3, 2 and 1.
Show the answer and solution
Answer: 10
The first one shook hands with four, the next one shook hands with three new friends, then two and one. Total 4 + 3 + 2 + 1 = 10.