function formatCurrency(num) {

num = num.toString().replace(/\$|\,/g,'');

if(isNaN(num))

num = "0";

sign = (num == (num = Math.abs(num)));

num = Math.floor(num*100+0.50000000001);

cents = num%100;

num = Math.floor(num/100).toString();

if(cents<10)

cents = "0" + cents;

for (var i = 0; i < Math.floor((num.length-(1+i))/3); i++)

num = num.substring(0,num.length-(4*i+3))+','+

num.substring(num.length-(4*i+3));

return (((sign)?'':'-') + num + '.' + cents);

}



function calc1(form) {

var rent

calc_rent = form.income.value * .30;

form.rent.value = formatCurrency(calc_rent);

}