JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://code.jquery.com/jquery-3.2.1.min.js"></script>
<input type="checkbox" value="2" /> <br>
<input type="checkbox" value="3" /> <br>
<input type="checkbox" value="4" /> <br>
<input type="checkbox" value="5" /> <br>
<input type="button" value="click" /> <br>

JavaScript

$('input[type=button]').click(function () {
	var checkboxes = $('input[type=checkbox]:checked');
  var result = 222;
  var sum = 0;
	for (var i=0; i < checkboxes.length; i++) {
    sum += Number(checkboxes[i].value);
  }
  result *= sum;
  alert(result);
})