function calc(){
  		if (isNaN(document.calculatorform.monthlylow.value) || (document.calculatorform.monthlylow.value==''))
  			document.calculatorform.monthlylow.value="Enter a number";
  		if (isNaN(document.calculatorform.monthlyhigh.value) || (document.calculatorform.monthlyhigh.value==''))
  			document.calculatorform.monthlyhigh.value="Enter a number";
  		if (isNaN(document.calculatorform.down.value) || (document.calculatorform.down.value=='')){
  			document.calculatorform.down.value="Enter a number";
  		return;
    }

    var yint = document.calculatorform.rate.options[document.calculatorform.rate.selectedIndex].value;
    var mint = yint / 100 / 12;
    var pmt = document.calculatorform.monthlylow.value;
    var n = document.calculatorform.term.options[document.calculatorform.term.selectedIndex].value;

    if (yint == 0){
      var pv = (pmt * n)
    }else{
      var pv = ((pmt) / (mint / (1 - (1 / Math.pow(1 + mint, n)))));
    } 

    pv = pv + eval(document.calculatorform.down.value);
    strpv = new String(pv);
    strpv = Math.floor(strpv);

    document.theform_1.MyPriceBottom.value=strpv;
  	if (isNaN(document.theform_1.MyPriceBottom.value))
  		document.theform_1.MyPriceBottom.value="Invalid Calculation";

    var pmt = document.calculatorform.monthlyhigh.value;
    if (yint == 0){
      var pv = (pmt * n)
    }else{
      var pv = ((pmt) / (mint / (1 - (1 / Math.pow(1 + mint, n)))));
    }

    pv =  pv + eval(document.calculatorform.down.value);
    strpv = new String(pv);
    strpv = Math.floor(strpv);

    document.theform_1.MyPriceTop.value=strpv;
  	if (isNaN(document.theform_1.MyPriceTop.value))
  		document.theform_1.MyPriceTop.value="Invalid Calculation";
    }