Yes, you can. Whenever you click on a field, check the “TYPE of Text Field” indicator in the top right corner of the field:
If it is a “C”, then it is a numeric field and you can directly use calculations.
In my “[PMW] Prompt with Multiple Windows” macro, I cascade the windows based on the number of prompts desired. While I'm certain the calculations can be refined, if you examine the macro, you'll discover a few reusable methods that you can incorporate into your own macros. For instance, to close the opened KME windows, you can utilize Dynamic Variable Names or, probably more efficient, variable arrays or JSON/dictionaries:
