improper matrix print out latex - matrix

Question

using Latex to print out a Matrix , I noticed I can not place the numbers under each other correctly
here is the code, I really appreciate your help
\begin{center}
$ABD=
\begin{bmatrix}
12610207.7\quad 5695754.3\quad 0\quad 0\quad 0\quad 0 \\
5695754.3\quad 10737818.8\quad 0\quad 0\quad 0\quad 0 \\
0\quad 0\quad 2800468.2\quad 0\quad 0\quad 0\\
0\quad 0\quad 0\quad 37.3\quad 125.08\quad 0.12\\
0\quad 0\quad 0\quad 125.08\quad 0.24\quad 0\\
0\quad 0\quad 0\quad 0\quad 0\quad 0.12
\end{bmatrix}
\end{center}
$
\begin{equation} \label{10}
\end{equation}
\end{center}

Answer 1

Matrix (and other tabular or array) constructions use & to denote the column delineation, not \quad:
\documentclass{article}
\usepackage{amsmath,siunitx}
\begin{document}
Using \verb|bmatrix|:
\[
ABD =
\begin{bmatrix}
12610207.7 & 5695754.3 & 0 & 0 & 0 & 0 \\
5695754.3 & 10737818.8 & 0 & 0 & 0 & 0 \\
0 & 0 & 2800468.2 & 0 & 0 & 0 \\
0 & 0 & 0 & 37.3 & 125.08 & 0.12 \\
0 & 0 & 0 & 125.08 & 0.24 & 0 \\
0 & 0 & 0 & 0 & 0 & 0.12
\end{bmatrix}
\]
Using \verb|array|:
\[
ABD =
\left[\begin{array}{#{}
S[table-format=9.1]
S[table-format=9.1]
S[table-format=7.1]
S[table-format=3.2]
S[table-format=3.2]
S[table-format=1.2]#{}}
12610207.7 & 5695754.3 & 0 & 0 & 0 & 0 \\
5695754.3 & 10737818.8 & 0 & 0 & 0 & 0 \\
0 & 0 & 2800468.2 & 0 & 0 & 0 \\
0 & 0 & 0 & 37.3 & 125.08 & 0.12 \\
0 & 0 & 0 & 125.08 & 0.24 & 0 \\
0 & 0 & 0 & 0 & 0 & 0.12
\end{array}\right]
\]
With bmatrix you don't have to specify the number of columns. However, there is a limit, but this can be extended.
siunitx was added to align the columns inside the array in a specific table-format way. Using a column specification #{}*{6}{c}#{} would have worked to produce a similar output as bmatrix.