Is it okay if math questions are ended with exclamation mark (!)? [closed]
Solution 1:
There are no "official" rules for how you combine symbolic math expressions with the surrounding natural language, but you should obviously avoid ambiguity. Putting an exclamation mark right after a numeric expression where it could be interpreted as a factorial is likely to be confusing.
Also, conventional math writing (at least what I'm familiar with) is pretty dry and unemotional, so readers are more likely to interpret an ambiguous $!$ as a factorial than as an exclamation.