I have a .aspx page in .NET that calls a javascript function. (which is in the .html code behind of the page) I use the following code to call the function in the .aspx page:

StringBuilder checkForAcrobat = new StringBuilder();
checkForAcrobat.Append("<script language='javascript'>");
checkForAcrobat.Append("checkAcrobatVersion();");
checkForAcrobat.Append("</script>");
RegisterStartupScript("checkForAcrobat", checkForAcrobat.ToString());

How can I return a value from this javascript function back to my .aspx page, and use if for further evaluation? I'm very new to javascript, so I'm not sure if I'm approaching this in the right way.
Say, for instance, in my example, the function checkAcrobatVersion returns the acrobatVersion. How can I return the acrobatVersion, so I can use it in my .aspx code page? Any help in this matter would be GREATLY appreciated. I have searched and searched, but could not find anything that helps.