Yes there are
For example promile or per mille (‰) for 1/1,000th of something, which is used for describing water salinity and some other concentrations that need more precision.
I encountered in middle school geography class as part of standard school programme (the chapter/section/etc. on oceans), so I expect that yes, it should be recognisable. There ...
This is an archaism that survives in Indian English. When I learned the times tables in the 70s, this is how I did it: "1 into 1 is 1", "1 into 2 is 2" etc. We also were taught '4 by 2 is 2', with 'by' standing for division.
You can see 17th and 18th century references to this usage, e.g., 'for two into two is Four' (Henry More, 1712); 'for two into three ...
Use parentheses to clearly convey your message.
We know (a > b), (c > d), (e > f), and (f > g).
We know (a > b, c > d, e > f), and (f > g).
Both of those are valid interpretations with different meanings, but you can clarify which is meant through parentheses.
You said "this should be technical", so what you provided would suffice for most audiences.
If this is the only part of the text that is utilizing the equation is the one sentence, then doing it as a parenthetical as you did is fine.
You could restructure the sentence to remove the parenthetical:
If you are fixing a 10 days port call in a month, having ...