The LaTeX command for variance is \operatorname{Var} (variance).
\operatorname{Var}Writing a paper? The table generator and the BibTeX cleaner are one click away, no account.
Write \operatorname{Var} inside math mode, that is between $…$ for inline math or in a \[ … \] or equation block for display math. This symbol needs the amsmath package, so add \usepackage{amsmath} to your preamble.
Notation varies between fields: whichever form of \operatorname{Var} you choose, define it once with \newcommand and reuse it.
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\mathbb{E}\mathbb{P}\operatorname{Cov}\operatorname{Cor}\mathds{1}\mathcal{N}\mathrel{\perp\!\!\!\perp}\xrightarrow{d}\xrightarrow{p}\xrightarrow{a.s.}\overset{\text{iid}}{\sim}Statistics and probability symbols in LaTeX: the full table or search all 350+ LaTeX symbols.
Use \operatorname{Var} in math mode after adding \usepackage{amsmath} to your preamble. For example, $\operatorname{Var}$.
It comes from the amsmath package: add \usepackage{amsmath} to your preamble.