There are specific methods that help in aligning table contents by decimal point.  Rather than using spaces, and other artificial methods, one should use the built-in formatting tools offered by their word processor.  In Microsoft Word there is a specific tab option which can be used in tables.  My outline of how to do this is below, or you can read about it on the Microsoft Office support website as well.

2)  Select the Decimal menu item.

3)  Select the numbers to align and then click in the ruler to insert the Decimal Tab.  Note how the numbers are now aligned by the decimal point.