Napr. takto:

<form method="get" name="form1_in">
<p>
	Bývaš na Slovensku?
	<input type="radio" name="N001" value="-5" checked>Áno
	<input type="radio" name="N001" value="0" >Nie<br>
</p>
<p>
	Žiješ v meste?
	<input type="radio" name="N002" value="8" checked>Áno
	<input type="radio" name="N002" value="0" >Nie<br>
</p>
<p>
	<input type="submit" value="VYPOCET" />
	<input type="reset" value="RESET">
</p>
<p>
	Výsledok: <input name="form1_out" size="10" /> %
</p>
</form>
<script>
document.forms['form1_in'].onsubmit = function() {
	var els = this.elements;
	var sum = 10;
	for (var i = 0, n = els.length; i < n; ++i) {
		var el = els[i];
		if (el.type == 'radio' && el.checked)
			sum += +el.value;
	}
	this.form1_out.value = sum;
	return false;
};
</script>