One of the great principles of information production is:
Separation of Content and Presentation
The more separate they are, the more you can change one without affecting the other. And the more you can make changes fast.
You already know how to do this. Styles are one example. Another is the automatic number formatting you can apply in spreadsheets. Typically this is for numbers that express dates, dollars, percentages, etc. Here's the spreadsheet with no formatting, and below with automatic currency formatting.
You might not know yet, however, that you have the same abilities with numbers in Writer tables. Here's the same information in a table.
To quickly apply or change the number formatting, select the cell or cells, right-click, and choose Number Format.
In the window that appears, select the format you want. First select the Category, then the Format. You can fiddle around with the options below the lists, including number of decimal places.
Click OK, and you've got the formatting. If you change your mind later and want different formatting, it's easy to change; just repeat this procedure and pick different options.