function CalculateTotals(){
	

f=document.order_form;
f.postagecosts.value=parseFloat(f.num_packs.value) 
													*parseFloat(f.postage.value);
f.subtotal.value=parseFloat(f.card_value.value)
										*parseFloat(f.num_packs.value);
f.total.value=parseFloat(f.card_value.value)
										*parseFloat(f.num_packs.value)
										+parseFloat(f.postagecosts.value);}


function checkforblanks()
	{
	for (var i = 0; i < arguments.length; i += 2)
		{
		if (!arguments[i])
			{alert("Please enter " + arguments[i+1] + ".");return false;}
		}
	return true;
	}

function validate()
	{
	// Make sure none of the required fields are empty
	var isFull = checkforblanks(document.order_form.f_name.value, "your  first name",
					document.order_form.s_name.value, "your surname",
					document.order_form.street.value, "your street address",
					document.order_form.suburb.value, "your suburb",
					document.order_form.city.value, "your city",
					document.order_form.email.value, "your email address",
					document.order_form.phone.value, "your phone number"
					);
	if (!isFull)
		{return false;}
	}