Inline: $\alpha + \beta = \gamma$ and $E = mc^2$.
Fractions: $\frac{a+b}{c}$ and $\frac{1}{2}$.
Roots: $\sqrt{x^2 + y^2}$.
Subscripts and superscripts: $x_i^2$ and $a_{n+1}$.
Greek: $\Sigma$, $\Pi$, $\Delta$, $\Omega$.
Operators: $\sum_{i=1}^{n} i$ and $\int_0^\infty e^{-x} dx$.
Blackboard bold: $\mathbb{R}$, $\mathbb{Z}$, $\mathbb{N}$.
Font commands: $\mathrm{id}$ and $\mathsf{Set}$ and $\text{hello}$.
Display math:
$$\sum_{i=1}^{n} i^2 = \frac{n(n+1)(2n+1)}{6}$$
$$\int_0^\infty e^{-x^2} dx = \frac{\sqrt{\pi}}{2}$$