function update_text() {
	var hay = getValue('hay');
	var carrots = getValue('carrots');
	var bells = getValue('bells');
	var total = 50 * bells + 30 * hay + 10 * carrots;
	var out = 'You are ordering '
		+ pretty_num(hay) + ' bushel' + pluralise(hay) + ' of hay, '
		+ pretty_num(carrots) + ' carrot' + pluralise(carrots)
		+ ', and ' + pretty_num(bells) + ' shiny bell' + pluralise(bells)
		+ ', at a total cost of <strong>' + pretty_num(total)
		+ '</strong> gold pieces. Thank you.';
	document.getElementById('preview').innerHTML = out;
}
function pretty_num(n) {
	n += '';
	var o = '';
	for (i=n.length; i>3; i-=3) {
		o = ',' + n.slice(i-3, i) + o;
	}
	o = n.slice(0, i) + o;
	return o;
}
function pluralise(n) {
	if (n!=1) return 's';
	return '';
}