AngularJS - Allow a calculated input to be editable <p>I have a basic addition calculator that looks like this:</p> <pre><code>&lt;!DOCTYPE html&gt; &lt;html ng-app&gt; &lt;head&gt; &lt;script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/angularjs/1.4.5/angular.min.js"&gt; &lt;/script&gt; &lt;/head&gt; &lt;body&gt; &lt;input type="number" ng-model="input1" /&gt; + &lt;input type="number" ng-model="input2" /&gt; = &lt;input type="number" ng-model="input1 + input2" /&gt; &lt;/body&gt; &lt;/html&gt; </code></pre> <p>Which looks like this:</p> <p>2 + 3 = 5</p> <p>I now have a requirement to make the third input editable and when changed it changes the value in the first input so that the numbers add up. So in the above example, supposing I change 5 to 6 it will look like this:</p> <p>3 + 3 = 6</p> <p>But because the model of the third input is a calculation I can't edit it. Please can someone advise how can I make it so that all three inputs are editable and yet still perform the required calculation?</p>