How JSP call java function from class file

hi guys, i wanna know how JSP call and pass parameter to a java function from class file.


class file
-----------------------------------------
public double calcQty(double pPect, double tQty)
{
return (pPect * tQty / 100);
}
------------------------------------------

JSP file
-------------------------------------------
<jsp:useBean id = "pc" class="common.claim" scope="request" />
the following code is call the function from the class file
<%=pc.calcQty()%>

izzit correct or not?
if let say i wan to call the function at onClick, how to write the code?
if i wanna pass in parameter to that function, how to write?
plz someone help. thx