var bTold = false;          
function isNumeric(strString) {                         
    var strValidChars = "0123456789";
    var strChar; 
    var blnResult = true;
    if (strString.length == 0) return false; 
    for (i = 0; i < strString.length && blnResult == true; i++) {    
        strChar = strString.charAt(i);   
        if (strValidChars.indexOf(strChar) == -1) {      
            blnResult = false;   
        }
    }
    return blnResult;                       
}                       
function pagesUp() { 
	document.getElementById('pages').value++;
	var iPages = document.getElementById('pages').value; 
	if (iPages > 18) {    
		document.getElementById('pages').value = 18;     
		alert('Please email ideas@youds.com for a custom quote');                         
	}
	calcPrice();                        
}                       
function pagesDown() {               
	document.getElementById('pages').value = document.getElementById('pages').value-1;           
	var iPages = document.getElementById('pages').value; 
	if (iPages < 0) {    
		document.getElementById('pages').value = 0;
	}
	calcPrice();                        
}                      
function pagesValue() {                         
	var iPages = document.getElementById('pages').value; 
	if (!isNumeric(iPages)) {    
		document.getElementById('pages').value = ''; 
	} else if (iPages < 0) {     
		document.getElementById('pages').value = 0;     
	} else if (iPages > 18) {    
		document.getElementById('pages').value = 18;     
		alert('Please email ideas@youds.com for a custom quote');                         
	}
	calcPrice();                        
}                    
function calcPrice() {                          
	var iPages = document.getElementById('pages').value; 
	var iPrice = 0;                         
	if (iPages > 0) {    
		iPrice+=500; 
		iPages=iPages-1;    
		iPrice += iPages * 75;   
		document.getElementById('totalPrice').innerHTML = '&pound;'+iPrice.toFixed(2)+'+VAT';        
		var iDeposit =  (iPrice / 100) * 30;     
		var iDeposit =   Math.round(iDeposit / 10) * 10;     
		document.getElementById('depositPayment').innerHTML = '&pound;'+iDeposit.toFixed(2);          
		var iFirst = iDeposit + (iDeposit / 10);   
		var iFirst =   Math.round(iFirst / 10) * 10;
		document.getElementById('firstPayment').innerHTML = '&pound;'+iFirst.toFixed(2);          
		var iFinal = iPrice - (iDeposit + iFirst);   
		document.getElementById('finalPayment').innerHTML = '&pound;'+iFinal.toFixed(2);     
		document.getElementById('paymentInfo').style.display = 'block';                         
	} else {     
		document.getElementById('paymentInfo').style.display = 'none';                          
	}                        
}