Math.ceil в расчете js

function output() {
  var value1 = document.getElementById('value1').value;
  var value2 = document.getElementById('value2').value;
  var value3 = document.getElementById('value3').value;
  document.getElementById('result1').innerHTML = ((parseFloat(value1) + parseFloat(value2)) / parseFloat(value3)).toFixed(2);
}

<input id = "value1" type = "text" onchange = "output();" />
<span> + </span>
<input id = "value2" type = "text" onchange = "output();" />
<span> / </span>
<input id = "value3" type = "text" onchange = "output();" />
<p id = "result1"></p>