TeXstudio math notation

1.1 ∈ Z
$1 \in \mathbb{Z}$
where \mathbb{Z} represents a set of integers.
2. In LaTeX, you can use the \times command to represent multiplication symbols, for example: $2\times 3$ or$2\cdot 3$ . Among them, \cdot represents the multiplication sign.
3. Superscript ^ Subscript_
4. Fraction
\frac{}{}