function validateForm() {
	var form=document.eform;
	var myindex=form.factor.selectedIndex;

	if (document.eform.rDiameter.value == "")
		{
		alert("Enter Roll Diameter (inches).");
		document.eform.rDiameter.focus();
		return (false);
		}

	if (isNaN(document.eform.rDiameter.value))
		{
		alert("Roll Diameter must be a number.");
		document.eform.rDiameter.focus();
		return (false);
		}

	if (document.eform.cDiameter.value == "")
		{
		alert("Enter Core Diameter (inches).");
		document.eform.cDiameter.focus();
		return (false);
		}

	if (isNaN(document.eform.cDiameter.value))
		{
		alert("Core Diameter must be a number.");
		document.eform.cDiameter.focus();
		return (false);
		}

	if (document.eform.rWidth.value == "")
		{
		alert("Enter Roll Width (inches).");
		document.eform.rWidth.focus();
		return (false);
		}

	if (isNaN(document.eform.rWidth.value))
		{
		alert("Roll Width must be a number.");
		document.eform.rWidth.focus();
		return (false);
		}

	if (form.factor.options[myindex].value == "")
		{
		alert("Select Factor.");
		document.eform.factor.focus();
		return (false);
		}

	CalculateRollEstimation(form.rDiameter.value,form.cDiameter.value,form.rWidth.value,form.factor.options[myindex].value);
	return true;

}

function CalculateRollEstimation(rDiameter,cDiameter,rWidth,factor) {
	var RollEstimation = (rDiameter * rDiameter) - (cDiameter * cDiameter);
	RollEstimation = RollEstimation * rWidth * factor;
	document.eform.Answer.value = formatnumber(RollEstimation,0);

}

function formatnumber(val,places) {
    var power = 1;
    if (places> 0) {
		power = Math.pow(10,places);

    }

    // now we round the val to X decimal places.
    var roundedNum = (Math.round(val * power)/power) + "";

	// check the result for decimals
    var decpos = roundedNum.indexOf('.');


    if (decpos>= 0) {
	    var decDiff = places-(roundedNum.length-(decpos+1));

	} else {
		var decDiff = places;
		if (places> 0) {
			roundedNum += ".";

		}

	}
	// add missing zeros to satisify the decimal request.
	for (var x = 0; x < decDiff; x++) {
		roundedNum += "0";
	}
    return roundedNum;
}