# Should fractional units be displayed as fractions or as negative exponents

The comments in this post discuss this issue, though without a clear conclusion unless I'm missing something.

For something as simple as grams per mole for example, there are actually several ways of displaying the units:

1) g/mol
2) $\mathrm{g/mol}$
3) $\mathrm{g~mol^{-1}}$
4) $\mathrm{g\dot\ mol^{-1}}$
5) $\mathrm{\frac{g}{mol}}$

And probably more.

I suspect that 3 is the best way in-line and either 3 or 5 when not in-line? I don't know, that's why I'm asking ;)

But to reiterate my main question: should fractional units be displayed as fractions or as negative exponents. And if the answer is "depends", then on what?

• You should really stop by chat sometime, airhuff. Things like this get batted around a lot. (A lot of the time nothing ever really happens about them, but we talk about them... ;-) – hBy2Py Mar 25 '17 at 3:34
• @hBy2Py Try typing [chat] in a comment ;) Also, you either lost your mouth, or you forgot to close your parentheses. Tut-tut. – orthocresol Mar 25 '17 at 13:24
• @orthocresol [chat] doesn't go straight to Periodic Table, though. I used to double the parenthesis in this kind of situation, but I ended up deciding that I preferred the syntactic irregularity to the visual unpleasantness of the double-paren. (I'm one of those types that will use square brackets, curly braces, etc. in regular text.) – hBy2Py Mar 25 '17 at 13:55

In situations where the units are poorly formatted by whatever measure, though—misspelled, wrong punctuation, ambiguous, etc.—I'd be mildly in favor of establishing a semi-formal site-wide recommendation for how they be formatted. I tend to prefer $\#3$, myself, as it is cleaner than $\#4$ (despite Loong's comment using $\#4$ at the linked post) and usually makes it less ambiguous as to which quantities are in the numerator/denominator. That said, $\#2$ involves a lot less typing, which is worth something. I do think any recommendation should include the use of MathJax since exponents will often be required, which leaves out $\#1$. Per Loong's other comment $\#5$ should apparently be shunned (SHUNNED) in polite technical discourse. (Full disclosure: I've formatted inline units that way more than once. {{{SHAME}}})