For any sets $a_1$, $\cdots$, $a_n$ ($n \geq 3$), we write
\[\{a_1, \cdots, a_n\} = \{a_1\} \cup \cdots \cup \{a_n\}.\]
Note. Roster Notation is also known as Enumeration Notation.
For any sets $a_1$, $\cdots$, $a_n$ ($n \geq 3$), we write
\[\{a_1, \cdots, a_n\} = \{a_1\} \cup \cdots \cup \{a_n\}.\]
Note. Roster Notation is also known as Enumeration Notation.