## Precalculus (6th Edition)

Natural numbers are the counting numbers $1, 2, 3, ...$. Thus, the natural numbers less than 3 are and 2. This means that the set on the left side is $\left\{1, 2\right\}$. Two sets are equal if they have exactly the same elements. Note that $\left\{1, 2\right\} = \left\{1, 2\right\}$. The two sets have exactly the same elements therefore they are equal sets. Thus, the given statement is true.