About Tier 1 - Element
Focused around one main idea or observation.
Difficulty describes the challenge, not the solver. It is a Society guide rather than a formal academic level.
The tier is a Society guide to the amount of reasoning, technical work and insight a problem is expected to require. Your experience may vary depending on the topic and your background.
Hello, Everyone
Combinatorics / Counting Pairs - 2 min
Five people meet. Each person shakes hands with every other person exactly once, and nobody shakes their own hand. How many handshakes happen?
Assumptions
Count each handshake once, regardless of which person initiates it.
More Options for Hello, Everyone
Collection question · Revision 1 · ID: handshakes