// code that creates variables that where not in you snippet
var tr = document.querySelector('tbody tr');
var row = document.querySelector('thead tr');

var th = document.createElement('th');
th.className = "hours_used";
var text = document.createTextNode("Hours used")
th.appendChild(text);
row.appendChild(th);

var th = document.createElement('th');
th.className = "prognose_eks";
th.id = "digit_fast_header"
var text = document.createTextNode("Prognose exp")
th.appendChild(text);
th.style.display = "none";
row.appendChild(th);

var th = document.createElement('th');
th.className = "prognose_mail";
th.id = "digit_fast_header"
var text = document.createTextNode("Prognose mail")
th.appendChild(text);
th.style.display = "none";
row.appendChild(th);

var td = document.createElement('td');
td.className = "hoursUsed";
td.innerHTML = "<input type='number' disabled='disabled' id='result'>"
tr.appendChild(td);

var td = document.createElement('td');
td.className = "inputEks";
td.id = "inputEks" 
td.innerHTML = "<input type='number' class='input1' name = 'inpt[]' >";
tr.appendChild(td);
// new line
var inputEks = td.querySelector('input');

var td = document.createElement('td');
td.className = "inputMail";
td.id = "inputMail" 
td.innerHTML = "<input type='number' class='input2' name = 'inpt[]' >";
tr.appendChild(td);
// new line
var inputMail = td.querySelector('input');

// new code

inputMail.addEventListener('input', chnage);
inputEks.addEventListener('input', chnage);

function chnage() {
  var GNS_EKS_TIME = 9;
  var GNS_MAIL_TIME = 9;
  TimeSum = (parseInt(inputEks.value, 10) / GNS_EKS_TIME) + (parseInt(inputMail.value, 10) /   GNS_MAIL_TIME);
  console.log("########### TEST ############## " + TimeSum);
}

<table>
<thead><tr></tr></thead>
<tbody><tr><tr></tbody>
</table>