That is purely a matter of which font you apply to the text. Most fonts are
"proportional", in which different letters have different widths. Only a
relative few are "nonproportional" or fixed-width. The most commonly
available nonproportional fonts are Courier New and Lucida Sans Typewriter.

However, in many nonproportional fonts the digits are all the same width so
that they will line up in columns, as long as you get the rightmost digits
to align. The tool to make that happen is the decimal tab. At the left end
of the horizontal ruler is a button with what looks like a bold L on it.
Click that button several times until you get an upside-down T with a dot.
Then click on the ruler at the position where the units digit should align.
Then press the Tab key and enter your number; hit Enter, hit Tab, enter the
next number; etc. See http://word.mvps.org/FAQs/Formatting/SettingTabs.htm
for more info.