$\sin x + \ln y + \operatorname{sgn} \, z$
$\nabla \partial x dx \dot x \ddot y$
$a^{2+2}$
$\sum_{k=1}^N k^2$ $\alpha \beta \gamma \delta \epsilon \zeta \eta \theta \iota \kappa \lambda \mu \nu \xi \omicron \pi \rho \sigma \tau \upsilon \phi \chi \psi \omega$