function fire_insurance() {
	var sum;
	var premium = "";
	if (document.form1.sum_insured.value == "") {
		alert("請輸入投保金額。");
		document.form1.sum_insured.focus();
		return;
	}
	sum = document.form1.sum_insured.value;
	if(sum <= 5000000)
		premium = sum * 0.0005;
	else if(sum > 5000000)
		premium = sum * 0.0004;
	if(premium < 400)
		premium = 400;
	premium = Math.round(premium);
	document.form1.fire_premium.value = premium;
}
function isNum(obj) {
	var i, ch;
	var str = obj.value;
	if (str.substring(0,1) == "."){
		alert("小數點不能出現於數字第一個位。")
		return false;
	}else{
		for (i = 0; i < str.length; i++) {
			ch = str.substring(i, i + 1)
			if ((ch < "0" || "9" < ch) && ch != '.') {
				alert(ch + "不是數字。")
				obj.focus();
				return false;
			}
		}
		return true
	}
}
function moneyFormat(input) { 
	var dollars = Math.round(input);
	var tmp = new String(input);
	for (var decimalAt = 0; decimalAt < tmp.length; decimalAt++) {
		if (tmp.charAt(decimalAt)==".") break;
	}
	var cents  = "" + Math.round(input * 100);
	cents = cents.substring(cents.length-2, cents.length);
	dollars += ((tmp.charAt(decimalAt+2)=="9")&&(cents=="00"))? 1 : 0;
	return dollars + "." + cents;
}