[Tex/LaTex] 1st, 2nd and i-th?

math-modenumberingtypography

Assume I wish to refer to the i-th object, or the n-th function out of some set, where i and n are letters and not numbers (as in "Multiply the $j$th row with the $i$th column and store the result in the $k$th memory cell, where $k=i+j$")

How do you suggest to write it?

$n$th is just confusing, $n$-th seems weird, and $n^{\text{th}}$, which is my current choice, is (pardon me) simply ugly.

Any suggestions?

In my experience $n$th is most widely used (like here). Personally I don't think it's ugly compared to the other two options and I think it's quite readable.