modifica da somma a molt

[beppenet]

Ciao ragazzi!
Come posso modificare questo script perchè faccia la moltiplicazione ma con massimo 2 cifre decimali?? :master:
<FORM name=somma>
<INPUT
onblur="somma.risultato.value=Number(somma.operand o1.value)* Number(somma.operando2.value)"
name=operando1 size="20"> +
<INPUT
onblur="somma.risultato.value=Number(somma.operand o1.value)* Number(somma.operando2.value)"
name=operando2 size="20"> = <INPUT value=0 name=risultato size="20">


<INPUT onclick="somma.risultato.value=Number(somma.operan do1.value)+ Number(somma.operando2.value)" type=button value="Fai la somma!">
</FORM>

[$$$]

  <form name="base">
    <input name="op1" value="0" type="text" onblur="mul(this.form.op1.value, this.form.op2.value, this.form.ans);" /> * 
    <input name="op2" value="0" type="text" onblur="mul(this.form.op1.value, this.form.op2.value, this.form.ans);" /> = 
    <input name="ans" value="0" type="text" /> 
    <input type="button" value=" [moltiplica] " onclick="mul(this.form.op1.value, this.form.op2.value, this.form.ans);" />
  </form>

  <script type="text/javascript">
  <!--

    function mul (source1, source2, answer)
    {
      source1 = parseFloat(source1);
      source2 = parseFloat(source2);

      if (!answer || isNaN(source1) || isNaN(source2))
        return;

      answer.value = Math.round (source1*source2*100) / 100;
    }

  //-->
  </script>

[beppenet]

Grazie! per quanto riguarda la somma con soli 2 decimali...è lo stesso??

[$$$]

  <form name="base">
    <input name="op1" value="0" type="text" onblur="add(this.form.op1.value, this.form.op2.value, this.form.ans);" /> + 
    <input name="op2" value="0" type="text" onblur="add(this.form.op1.value, this.form.op2.value, this.form.ans);" /> = 
    <input name="ans" value="0" type="text" /> 
    <input type="button" value=" [addiziona] " onclick="add(this.form.op1.value, this.form.op2.value, this.form.ans);" />
  </form>

  <script type="text/javascript">
  <!--

    function add (source1, source2, answer)
    {
      source1 = parseFloat(source1);
      source2 = parseFloat(source2);

      if (!answer || isNaN(source1) || isNaN(source2))
        return;

      answer.value = Math.round ((source1+source2)*100) / 100;
    }

  //-->
  </script>

si è lo stesso: basta solo avere cura delle parentesi per favorire la precedenza all'addizione.