Euler’s Formula

V − E + F = 2

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Euler: $V - E + F = 2$ for every convex polyhedron.
• Use it to find a missing count (like the vertices of a soccer ball).
• Shapes with holes give 2 − 2g instead, a first taste of topology.

Steps

1. A cube’s numbers
2. Euler’s polyhedron formula
3. Soccer ball
4. Cutting corners
5. Where soccer balls come from
6. With a hole