Trying to calculate value from selected option using Javascript

`Hi, I am trying to get the option valud from the dropdown and use Javascript to calculate an output. For exmple option 3 is selected I need to show the value of 3 * 13.95 and ge the correct output of 41.85.

html code below.

<div class="">
  Red Leicester Cheese
  <br>
  13,25€ per kilo
 <select id="old english" name="oldenglish" onchange="calcVals">
<option value="0" disabled="" selected=""></option>
<option value="1">1 Kilo</option>
<option value="2">2 Kilos</option>
<option value="3">3 Kilos</option>
<option value="4">4 Kilos</option>
<option value="5">5 KiLOS</option>

 </select>
 <br><label for="weight">Enter Weight</label>
  <br>
  <input type="number">
  </select>

  Textbox :

<input name="totalAmount" id="totalAmount" type="text" readonly>

 </div>

Javascript below

function calcVals() {

  var e = document.getElementById("old english");

  var selFrst = e.options[e.selectedIndex].value;

  var totalCal = +selFrst * 13.95;
  document.getElementById("totalAmount").value = totalCal;
}

I hope someone can help. Thanky you

I tried to get Javascript to calculate a sum and give an output once a value was selected from the drop down but it return no value.