Question

A group of 53 friends meets for lunch. They greet each other by exchanging fist bumps. How many fist bumps are exchanged if each friend must bump with each of the 52 others?

Answer 1

There are 53 people. The formula is

Bumps = n*(n - 1)/2

n = 53

bumps = 53*52/2 = 1378 bumps. Here's a question for you. Can you ever get an odd number of bumps? The answer is no.