Hello nanaseailie. Often, a simple way to find LaTeX code for a particular symbol is to google it. For example, you could google
square root symbol LaTeX and Google will show the code at the top of the search-results list. Jeff's suggestion (using 'Reply' to see code in someone else's post) is good. Another way is to right-click on existing LaTeX in the forum and then use the pop-up menu to see the code. That method is described in
this thread; also included is a link to a wiki page that lists math symbols. If you have any other LaTeX questions, you may add them to this thread or start a new thread on the Administrative Issues board. Cheers