Just a technical note on all this: I7 isn’t going to be able to parse something like “divide 20 by 4” out of the box, because you are limited to one value when defining a command’s grammar. There are ways around this, though, such as parsing commands containing “divide” iteratively to grab second, third, or more values. Here are some links to discussions about matching more objects and texts (a kind of value) than Inform normally allows:
groups.google.com/group/rec.arts … 61b9823115
groups.google.com/group/rec.arts … b1dadc372f
https://intfiction.org/t/actions-involving-more-than-2-things/1947/1
None of these will do just what you’re looking for, but the code examples should give you some ideas.
–Erik