<form name="waris" id="wrapped" action="hasil" method="POST">
                            <input type="radio" value="100" name="harta" onFocus="startCalc();" onBlur="stopCalc();"></br>
                            <input type="radio" value="200" name="harta" onFocus="startCalc();" onBlur="stopCalc();"></br>
                            <input type="text" name="sisa_harta" class="required form-control" placeholder="Total harta siap di bagi" onchange='tryNumberFormat(this.form.thirdBox);' readonly>
    </form>
<script type="text/javascript">
//Form Jumlah Harta
function startCalc(){
interval = setInterval("calc()",1);}
function calc(){
one = document.waris.harta.value;
document.waris.sisa_harta.value = (one * 1);}
function stopCalc(){
clearInterval(interval);}
</script>