For example, can I write "10," if I want to write the number 10 with two significant figures. I know it can be done in some countries using a decimal point, but where I'm from, the decimal comma is used instead of the decimal point.
To clarify, I am wondering whether this is a standard or accepted way of writing 10 with two significant figures. I know e.g. that in the US I can write the number 5200 as "5200." if I want to let the reader know that the number has four significant figures. However in many countries in Europe, a decimal comma is used instead of a decimal point. So my question in this case would be if I could write 5200 as "5200," to signify that the number has 4 significant figures.
My problem is that I am unsure whether it is a generally accepted way to write the numbers with a comma. And the reason why I would rather not use scientific notation is because for small numbers, like 10 or 500, I sometimes find it rather clunky in text.
These ambiguities can also be resolved using scientific notation; the number $10$ to one significant figure (s.f.) is $1\times10^1$, to 2 s.f. it's $1.0\times10^1$, and so forth.
EDIT: I have never seen a comma used indicate s.f. I do remember in chemistry class that an underline could be used in this way; ie. the number $500$ to 2 s.f. is $5\underline{0}0$, to 3 s.f. is $50\underline{0}$, etc. Perhaps you might find this method convenient for smaller numbers.