JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.2/jquery.min.js"></script>
<div>Урон оружием <input id="damage" type="text"></div>
<div>Количество оружия <input id="number" type="text"></div>
<div>Криты, % <input id="critical" type="text" value="10"></div>
<div>акция + <select id="action">
  <option value="100">100%</option>
  <option value="300">300%</option>
  </select></div>
<div><button type="button" id="calc">Посчитать</button></div>
<div>Урон с критами: <span id="total"></span></div>

CSS

div{
  margin-bottom: 10px;
}
input{
  padding: 5px 10px;
  margin-left: 10px;
}

JavaScript

$("#calc").click(function() {
  var damage = $('#damage').val();
  var number = $('#number').val();
  var critical = $('#critical').val();
  var action = $('#action').val();
  var total;
  total = ((damage*2*critical)+(damage*(100-critical)))/100*number;
  total = total+total/100*action;
  $('#total').html(total);
});