javascript - math leaving off a digit

Hi,

I have a javascript that converts numbers to decimals (adds decimals if needed and does simple math).  It uses three fields to autoFill the 4th.  Field 1 is addition.  Field 2 subtraction.  Field 3 addition.  Field 4 should reflect the calculation of 1,2,3.  The problem is this.  If I type 20 into field 1, field four shows 2.00... and NOT 20.00.  This si probably a simple fix, and this was working great when I was using onChange instead of onKeyPress.  

Code is below.  Thank you very very much ... Wendi~

<script type="text/javascript">
 
function calc(){
  one = document.autoSumForm16.budget_income1.value;
  two = document.autoSumForm16.budget_income2.value;
  three = document.autoSumForm16.budget_income3.value;
      if (one >'' && two > '' && three > '' ) {
      var sum  = parseInt(one) - parseInt(two) + parseInt(three);
      
      var num = new NumberFormat(sum).toFormatted();
      document.autoSumForm16.budget_income4.value = num;
	  document.autoSumForm16.budget_exp4.value = num;
      }
      else  
      {
            alert ('Please enter a number.  No commas or letters.');
            }
}
 
 
function CurrencyFormatted(amount)
{
        var i = parseFloat(amount);
        if(isNaN(i)) { i = 0.00; }
        var minus = '';
        if(i < 0) { minus = '-'; }
        i = Math.abs(i);
        i = parseInt((i + .005) * 100);
        i = i / 100;
        s = new String(i);
        if(s.indexOf('.') < 0) { s += '.00'; }
        if(s.indexOf('.') == (s.length - 2)) { s += '0'; }
        s = minus + s;
        return s;
}
 
 
</script> 
 
<!--- These three fields calc the one below.  I want it to be where simply typing being the calculation, and instantly changes
      the number below --->
<input type="Text"  name="budget_income1" style="text-align:right;" onKeyPress="calc();" value="0">
<input type="Text"  name="budget_income2" style="text-align:right;" onKeyPress="calc();" value="0">
<input type="Text"  name="budget_income3" style="text-align:right;" onKeyPress="calc();" value="0">
 
 
<!--- This is the field being calculated by the 3 above --->
<input type="Text"  name="budget_income4"  style="text-align:right;" value="#getform.budget_income4#">

Select allOpen in new window