Untitled

<html>
<form>
<input type="text" id="first" class="num">
<input type="text" id="second" class="num">
<input type="text" id="third" class="num">
<input type="button" value="GET" id="get" onclick="func()">
<p id="result"></p>
</form>
<script>
var num=document.getElementsByClassName('num')
var summ=0
function func(){
for (var i = 0; i < num.length; i++) {
                               summ=summ+Number(num[i].value)
}
    document.getElementById("result").innerHTML=summ;
               }
    </script>
</html>