function forbrugsberegner()
{
	
	var floor_size = $ID('floorSize');
	var floorValue = new Number(floor_size.value);
	
	var ltrColor = floorValue / 4;
	var ltrCleaner = floorValue / 10;
	
	ltrColor = Math.ceil(ltrColor);
	ltrCleaner = Math.ceil(ltrCleaner);
	
	$ID('stoneColorNeed').innerHTML = ltrColor;
	$ID('stoneCleanerNeed').innerHTML = ltrCleaner;
}

function $ID (id)
{
	if (!id) return;
	return document.getElementById(id);
}

window.onload = function()
{
	var table = $ID('forbrugsberegner');
	if (!table) return;
	
	var span1 = document.getElementById('forbrugsberegner').getElementsByTagName('span')[0]
	var span2 = document.getElementById('forbrugsberegner').getElementsByTagName('span')[2]
	//span1.innerHTML += 'ca ';
	//span2.innerHTML += 'ca ';
	//table.className = 'visible';
	
	var button = $ID('calculateNeeded');
	button.onclick = forbrugsberegner;
};