# Product of Number of Edges, Edges per Face and Faces of Tetrahedron

## Theorem

The product of the number of edges, edges per face and faces of a tetrahedron is $72$.

## Proof

A tetrahedron has:

- $6$ edges

and:

- $4$ faces.

Each face is a triangle, and so has $3$ edges.

Hence:

- $6 \times 4 \times 3 = 72$

$\blacksquare$

## Sources

- 1997: David Wells:
*Curious and Interesting Numbers*(2nd ed.) ... (previous) ... (next): $72$