Many software applications have to display series of numbers, for example statistical information, measurement values or financial data. Of course there are many ways to visualize values graphically with charts, but sometimes the user wants to see the actual values as numbers. The typical layout method to display numbers are tables.
Here are some guidelines you should follow when you have to display numbers in a table.
Integer numbers that are shown in a table column should be right-aligned, because the orders of magnitude of a number’s digits increase from right to left. Additionally you should choose a font with fixed-width digits for numbers. This ensures that digits with the same orders of magnitude line up. Thus the numbers can be compared more easily. The font itself doesn’t have to be a fixed-width font in general. Some proportional fonts with variable widths for letters have fixed-widths for digits, called tabular figures.
Non-integer numbers with decimal points should be aligned with their decimal points. The reason is the same as above: digits with the same orders of magnitude should line up. This can be a bit more effort to implement in your application than mere right-alignment, because components such as UI widgets or HTML tables usually don’t directly support this form of alignment.
However, you can implement it by using a font with tabular figures and then right-pad the numbers with spaces. Each of these spaces must have the same width as a digit, of course. This is the case with a fixed-width font, but there is also a special Unicode character for this purpose that can be used with proportional fonts and tabular figures: it’s called figure space and has the Unicode code point U+2007.