% si units
\usepackage{siunitx}
\sisetup{
	output-decimal-marker = {.}, 	% use point instead of comma in units
	per-mode = symbol 	% show units in compact fractions and not in big ones
}

%\usepackage{layouts} % convert units, useful to find out textwidth e.g. the \textwidth:
% "textwidth in cm: \printinunitsof{cm}\prntlen{\textwidth}"

% define units
% usage: si{\a} returns m², \SI{10.45}{\a} returns 10 m²
\DeclareSIUnit{\a}{m^2}
\DeclareSIUnit{\V}{m^3}
\DeclareSIUnit{\C}{\degreeCelsius}
\DeclareSIUnit{\deg}{\degree}
\DeclareSIUnit{\den}{\kilogram \per \cubic \meter}
\DeclareSIUnit{\c}{\newton \per \milli \meter}
\DeclareSIUnit{\mm}{mm}
\DeclareSIUnit{\amm}{mm^2}
\DeclareSIUnit{\imm}{mm^4}
\DeclareSIUnit{\kN}{\kilo \newton}
\DeclareSIUnit{\f}{MPa}
\DeclareSIUnit{\epcm}{\text{\euro} \per \cubic \meter}
\DeclareSIUnit{\pp}{\percent \per \percent}