jQuery(document).ready(function() {
        jQuery("#quantity").keydown(function(event) {
            // Allow only backspace and delete
            if ( event.keyCode == 46 || event.keyCode == 8 ) {
                // let it happen, don't do anything
            }
            else {
                // Ensure that it is a number and stop the keypress
                if (event.keyCode < 48 || event.keyCode > 57 ) {
                    event.preventDefault(); 
                }   
            }
        });
    });

    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 CalculateCost(){
        $radio = jQuery('input:radio[name=exit_signs_list]:checked').val();
        $quantity = parseInt(document.getElementById("quantity").value);
        $time = 8760;
        $watt = 0.18;
        $rate = 0.1;

        $kwh = ($watt * $time)/1000;
        $totalcost = $kwh * $quantity * $rate;
        document.getElementById("cost").innerHTML = formatCurrency($totalcost);

        jQuery("#Incandescent_compare").hide();
        jQuery("#Compact_compare").hide();
        jQuery("#Fluorescent_LED_compare").hide();

        jQuery("#"+$radio+"_compare").show();
        jQuery("#result").show();

    }