function total_score() {
    total = 0;
    for ( i = 0; i < document.f.elements.length; i++ ) {
        if ( document.f.elements[i].name != 'total' ) {
            if ( document.f.elements[i].checked ) {
                total += parseInt(document.f.elements[i].value);
            }
        }
    }
    
    document.f.total.value = total.toString();
}