# Cardinality/Examples/-1,0,1

## Example of Cardinality

Let $S_1 = \set {-1, 0, 1}$.

The cardinality of $S_1$ is given by:

$\card {S_1} = 3$

## Proof

$S_1$ has $3$ elements: $-1, 0, 1$.

Hence the result by definition of cardinality.

$\blacksquare$