Set Theory Symbols

Symbols are just representations of numbers, functions, or other mathematical characteristsics.

Question: Is 1 a symbol?

Obviously it is, 1 is a symbol or a representation of a number.

Lets take a look at another example: S = {B,C,D}

Take a look at the picture above. The circle represents the set S that contains the symbols B,C, and D. Symbols A and E are not contained in set S