You can use "dcolumn" package.
\usepackage{dcolumn}
\newcolumntype{.}{D{.}{.}{-1}}
\newcolumntype{d}[1]{D{.}{.}{#1}}
then, for example,
\begin{tabular}{l....}
Kosuke
On Tue, 13 May 2003, Olivia Lau wrote:
Dear Kosuke,
Do you know how to align the decimals in tables? I tried to make all of
my numbers left align with only one leading digit in each row before the
decimal, but the negative sign is making the decimals align funny:
0.012
-0.20
is an example. I don't use scientific notation, so I have a different
number of digits after each decimal place, otherwise I could right align
the column. Suggestions?
Thanks,
Olivia.