formattinghorizontal alignment
I want to display a centered formula to which can be referred as (*). Now, I have the following: 
But I want the formula to be more centered and the star to be right aligned. The code is now:
$$
\floor{7(n\pi - \floor{n\pi})} \qquad \qquad (*)
$$
By adding table-number-alignment=center (left, right and the default center-decimal-marker are the other choices) in the column specification, and removing the table-format=x.y specifiers, the 98 is more centered above the columns.
(I don't exactly understand what's going on, as the table-format option should set table-number-alignment to center, according to the manual.)
\documentclass{article}
\usepackage{threeparttable}
\usepackage{siunitx}
\usepackage{booktabs}
\usepackage{array}
\begin{document}
\begin{table}
\centering
\begin{threeparttable}
\caption{\textbf{\label{tab:ms-soziodemographische-parameter}blabla}}
\begin{tabular}{%
l
S[table-number-alignment=center]
S[math-rm=\mathit,input-symbols=(),table-number-alignment=center]
cc}
\toprule
& \multicolumn{2}{>{\centering}p{0.2\columnwidth}}{\textbf{Pat. mit Kopfschmerzen}} & \textbf{Pat. ohne Kopfschmerzen} & \textbf{p-Wert}\tabularnewline
\midrule
\midrule
\textbf{Anzahl} & \multicolumn{2}{c}{98} & 82 & \textbf{\textit{0,001}}\tabularnewline
\midrule
\textbf{Alter: Jahre (SD)} & 41 & (12,9) & 47,4 (12,6) & \textbf{\textit{0,001}}\tabularnewline
\midrule
\textbf{Geschlecht: n(\%)} & & & & \textbf{\textit{0,001}}\tabularnewline
- Weiblich & 78 & (79,6) & 47 (57,3) & \tabularnewline
- Männlich & 20 & (20,4) & 35 (42,7) & \tabularnewline
\midrule
\textbf{KD der MS: Jahre (SD)} & 11,2 & (8,6) & 13,7 (8,9) & 0,056\tabularnewline
\midrule
\textbf{Verlaufsform: n(\%)} & & & & \textbf{\textit{0,042}}\tabularnewline
- RRMS & 56 & (57,1) & 30 (36,6) & \tabularnewline
- SCP & 29 & (29,6) & 38 (46,3) & \tabularnewline
- PPMS & 11 & (11,2) & 13 (15,9) & \tabularnewline
- CIS & 2 & (2,0) & 1 (1,2) & \tabularnewline
\midrule
\end{tabular}
\end{threeparttable}
\end{table}
\end{document}
When you use the align environment (Insert --> Math --> AMS Align), the columns are aligned as rlrlrl..., as the usual use case is alignment around a relation. If you leave the odd columns (first, third, etc.) empty and place the content in the even columns, you will have just left alignment. This will, however, distribute the columns evenly over the text width, so if you have few/narrow columns, there may be a lot of white space between them.
An alternative then is to first add a normal display math environment (Ctrl + Shift + M) and within this add an aligned environment: Insert --> Math --> Aligned. This has the same alignment as align, so you would have to leave columns empty, but there won't be the extra space between them.
Best Answer
You have a choice between a six-pointed asterisk, generated by
\ast, and a five-pointed asterisk, generated by\star. Both of these macros need to be used in math-mode; choose whichever symbol you like better.I would also enlarge the floor-related symbols of the "outer"
\floordirective slightly as a visual aid towards parsing the equation.