Arithmetic operator

 <script language="javascript" type="text/javascript">
         function Sum() {
             var a = document.getElementById("A").value;
             var b = document.getElementById("B").value;
             var result = parseInt(a) + parseInt(b); 
            alert(result);
         }
     </script>  
    Enter two digit:
     <input type="text" id="A" name="A" />
     +
     <input type="text" id="B" name="A" />
       <input type="button"name="btnAdd"value="Add"onclick="Sum()" />  

For addition in Javascript code approch this code ..In the same way for subtract /division / multiplication change the code in "var result - / \ / * "

Run the code in the broswer