LaTeX Software
Custom Names for Equations
\begin{equation}\label{zzz}\tag{P1}
c^2 = a^2 + b^2
\end{equation}
Split-level Fractions
\documentclass{article}
\usepackage{xfrac}
\begin{document}
$\sfrac{12}{3}$
\end{document}
Tcolorbox
\usepackage{tcolorbox}
\begin{tcolorbox}[
boxrule = 0.5pt, colback = green!10!white,
grow to left by = -1in, grow to right by = -1in,
enlarge top by = 0.1in, enlarge bottom by = 0.1in]
$c^2=a^2+b^2$
\end{tcolorbox}
Change space in listing globally
\usepackage{enumitem}
\setlist[enumerate]{itemsep=1pt, topsep=1pt}
Align (right) in matrices
\begin{pmatrix*}[r]
1 & -2\\
-1 & 3
\end{pmatrix*}
Spacing in arrays
\[
\arraycolsep = 10pt
\def\arraystretch{2.2}
\begin{array}{c|c}
a & b\\
c & d
\end{array}
\]