Ok. I give up. I can't do this one by myself. Can someone please help?

All I want to do is have what ever fields the user inputs a number into added up and show the quantity totaled. Then in another place show the result of that quantity x 25.

Here is the page: http://www.rosofoto.com/price.html The first two calculators work. Its the third one, "Pricing by Number of Shoot Areas" that is giving me problems.

Here is my code with alot of it commented out because I was trying to eliminate what was causing problems. Thanks in advance for your help:

Code:
<script language="javascript" type="text/javascript">
var btn = document.getElementById('calculateRooms');
	btn.onclick = function() {
// get the input values
var ui1 = parseFloat('0'+document.getElementById('textfield1').value);
var ui2 = parseFloat('0'+document.getElementById('textfield2').value);
var ui3 = parseFloat('0'+document.getElementById('textfield3').value);
var ui4 = parseFloat('0'+document.getElementById('textfield4').value);
var ui5 = parseFloat('0'+document.getElementById('textfield5').value);
var ui6 = parseFloat('0'+document.getElementById('textfield6').value);
var ui7 = parseFloat('0'+document.getElementById('textfield7').value);
var ui8 = parseFloat('0'+document.getElementById('textfield8').value);
var ui9 = parseFloat('0'+document.getElementById('textfield9').value);
var ui10 = parseFloat('0'+document.getElementById('textfield10').value);
var ui11 = parseFloat('0'+document.getElementById('textfield11').value);
var ui12 = parseFloat('0'+document.getElementById('textfield12').value);
var ui13 = parseFloat('0'+document.getElementById('textfield13').value);
var ui14 = parseFloat('0'+document.getElementById('textfield14').value);
var ui15 = parseFloat('0'+document.getElementById('textfield15').value);
var ui16 = parseFloat('0'+document.getElementById('textfield16').value);
var ui17 = parseFloat('0'+document.getElementById('textfield17').value);
var ui18 = parseFloat('0'+document.getElementById('textfield18').value);

// get the elements to hold the results
var RoomsTotal = document.getElementById('RoomsTotal');
// create an empty array to hold error messages
//	    var msg = [];
// check each input value, and add an error message to the array if it's not a number
//	    if (isNaN(textfield1)) {
//	        msg.push('X is not a number');
//	    }
//	    if (isNaN(textfield2)) {
//	        msg.push('Y is not a number');
//	    }
//	    if (isNaN(textfield3)) {
//	        msg.push('Z is not a number');
//	    }
// if the array contains any values, display the error message(s) as a comma-separated string in the first <span> element
//	    if (msg.length > 0) {
//	        RoomsTotal.innerHTML = msg.join(', ');
//	    } else {
RoomsTotal.innerHTML = 'Total quantity of Rooms are: ' + (ui1 * 1) + (ui2 * 1) + (ui3 * 1) + (ui4 * 1) + (ui5 * 1) + (ui6 * 1) + (ui7 * 1) + (ui8 * 1) + (ui9 * 1) + (ui10 * 1) + (ui11 * 1) + (ui12 * 1) + (ui13 * 1) + (ui14 * 1) + (ui15 * 1) + (ui16 * 1) + (ui17 * 1) + (ui18 * 1) ;
//		}
	};
</script>