Calculate sum of values on text-boxes based on checkbox checked
<p>I want to add total sum in the text boxes based on the checkbox checked. But my text-box values varies dynamically based on the user choice, how to solve this?</p>

<pre><code>function UpdateCost() {
  var sum = 0;
  var gn, elem;
  for (i=0; i&lt;5; i++) {
    gn = 'game'+i;
 elem = document.getElementById(gn);
  if (elem.checked == true) { sum += Number(elem.value); }
 }
 document.getElementById('totalcost').value = sum.toFixed(2);
} 

&lt;html&gt;

&lt;input type="checkbox" id='game0' value="9.99"  onclick="UpdateCost()"&gt;Game 1 ( 9.99)&lt;br&gt;
&lt;input type="checkbox" id='game1' value="19.99" onclick="UpdateCost()"&gt;Game 2 (19.99)&lt;br&gt;
&lt;input type="checkbox" id='game2' value="27.50" onclick="UpdateCost()"&gt;Game 3 (27.50)&lt;br&gt;
&lt;input type="text" id="totalcost" value=""&gt;
</code></pre>

<p></p>

<p>The problem is the third value changes based on the other dropdown list</p>

<p>i have done something to generate the result of third but could not bind that value to checkbox value dynamically. here is the code below</p>

<pre><code>&lt;select ng-model="num1" ng-init="1"&gt;
 &lt;option selected ="selected" value="1"&gt;1
&lt;option value="2"&gt;2
 &lt;option value="3"&gt;3
&lt;/select&gt;

&lt;input type="number" id="txt2" value="{{num1*1000}}" readonly="true"&gt;
</code></pre>