How to make a row in a table with the sum of all the numbers in a column? Javascript beginner

Without further due, this is my problem: The created table is basically a form that takes a number in a loop and it calculates that number squared and factorial of it. I have managed to do that successfully but next problem Im encountering is I need to add sum of elements at the bottom of the table for all three columns.
Much appreciated.

<script>
        function tablica() {
            var nr = document.getElementById("broj").value
            if (nr < 2) {
                document.getElementById("rezultat").innerHTML = "Prilagođeno samo za rad s brojevima većim od 1";
                window.alert("Unijeli ste broj " + broj.value + ", a taj broj je manji od 2...");
            } else if (nr >= 2) {
                var rez = "<table id='tablica'><tr><th>N</th><th>N²</th><th>N!</th></tr>";
                var faktorijela = 1;
            }
            for (var i = 1; i <= nr; i++) {
                rez = rez + "<tr><td>" + i + "</td><td>" + i * i + "</td><td>" + (faktorijela = faktorijela * i) + "</td></tr>";
            }
            rez = rez + "</table>"

            var rezTablica = document.getElementById("rezultat");
            rezTablica.innerHTML = rez;
        }
    </script>

>Solution :

I have created variables sum1, sum2 and sum3 to store each column’s sum.

Please see snippet below :

function tablica() {
            var sum1 = 0, sum2 = 0, sum3 = 0;
            var nr = document.getElementById("broj").value
            if (nr < 2) {
                document.getElementById("rezultat").innerHTML = "Prilagođeno samo za rad s brojevima većim od 1";
                window.alert("Unijeli ste broj " + broj.value + ", a taj broj je manji od 2...");
            } else if (nr >= 2) {
                var rez = "<table id='tablica'><tr><th>N</th><th>N²</th><th>N!</th></tr>";
                var faktorijela = 1;
            }
            for (var i = 1; i <= nr; i++) {
                let val1 = i;
                let val2 = i * i;
                let val3 = (faktorijela = faktorijela * i);
                rez = rez + "<tr><td>" + val1 + "</td><td>" + val2 + "</td><td>" + val3 + "</td></tr>";
                sum1 = sum1 + val1;
                sum2 = sum2 + val2;
                sum3 += sum3 + val3;
            }
            rez = rez + "<tr><td>" + sum1 + "</td><td>" + sum2 + "</td><td>" + sum3 + "</td></tr>";
            rez = rez + "</table>"

            var rezTablica = document.getElementById("rezultat");
            rezTablica.innerHTML = rez;
        }

<input id="broj" type="text">
<button onclick="tablica()">Test</button>
<div id="rezultat">
</div>