Follow your curiosity

What discovery has been shared with you?

FACTREE gives you something interesting to discover every day — and something worth talking about together.

Start with one fact. Explore it, go deeper, then follow whichever branch catches your imagination.

Choose subjects for a surprise

Exploring any topic

Begin your discovery

Your next discovery is one click away.

Choose one or more subjects above, or leave Any Topic selected and let curiosity decide.

Mathematics

Expected Value

Quick fact

In a fair coin flip, the expected value of winning $1 for heads and losing $1 for tails is $0—the game is 'fair' because the long-run average is exactly zero.

Why this is interesting

Imagine you’re offered a coin flip: heads you win $100, tails you lose $50. Would you play? Intuition might say yes, but the real answer lies in a simple calculation that reveals the 'expected' payoff—and it might surprise you.