function weightcalculator(weightprice) {
var weight = $('weight').value;
var price = (weight / 100) * weightprice;

price = Math.round(price*100)/100;
price = price.toFixed(2);

$('price').setHTML('<strong>Price: &pound;'+price+'</strong>');

}

function quantitycalculator(quantity,price) {

price = quantity*price;
price = price.toFixed(2);

$('price').setHTML('<strong>Price: &pound;'+price+'</strong>');

}