This may even be more of a bug. Currently, the spellchecker counts things like “100m” and “200ft” as misspelled. That’s really annoying when doing work that involves a lot of measurements.
Count any number followed by SI units as valid spellings. If set to the US spellcheck dictionary, maybe also count Imperial as spelled right. I would even be fine if any mixed combo of numbers and letters was ignored by the spellcheck altogether.
Current workaround (optional)
No realy good workarounds I can see. Adding them to the dictionary bloats like crazy. Turning off the spellcheck means you don’t get any spell help. So I guess… for now… just deal with it…
I assume this is because most units are meant to have a space between the quantity and the unit:
12 km, not 12km
7 g, not 7g
37 m, not 37m
40 kV, not 40kV
100 mA, not 100mA
From the official SI brochure:
5.4.3 Formatting the value of a quantity.
The numerical value always precedes the unit and a space is always used to separate the unit from the number. (…) The only exceptions to this rule are for the unit symbols for degree, minute and second for plane angle, °, ′ and ′′, respectively, for which no space is left between the numerical value and the unit symbol.