SO - 22536448 (source: http://jsfiddle.net/tahongtrung/9W8qh/196/)

fiddle.css

body {
    background: black;
    color: #d5d4d4;
    font-family: Helvetica, Arial, sans-serif;
    font-size: 12px;
    margin: 0;
    overflow-x: auto;
    padding: 30px;
}
table {
    background: #030303;
    border-collapse: collapse;
    border: 3px #393939 solid;
    color: #d5d4d4;
    margin: 1em 1em 1em 0;
}
thead {
    border-collapse: collapse;
    color: #d5d4d4;
}
th, td {
    border: 1px #aaa solid;
    padding: 0.2em;
}

fiddle.html

<table>
    <thead>
        <tr>
            <th>MAX ATK</th>
            <th>MAX DEF</th>
            <th>MAX HP111</th>
            <th>Overall</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td class="combat">8170</td>
            <td class="combat">6504</td>
            <td class="combat">6050</td>
            <td class="total-combat"></td>
        </tr>
        <tr>
            <td class="combat">8500</td>
            <td class="combat">10200</td>
            <td class="combat">7650</td>
            <td class="total-combat"></td>
        </tr>
        <tr>
            <td class="combat">9185</td>
            <td class="combat">7515</td>
            <td class="combat">9185</td>
            <td class="total-combat"></td>
        </tr>
    </tbody>
</table>

fiddle.js

$(document).ready(function () {
    //iterate through each row in the table
    $('tr').each(function () {
        //the value of sum needs to be reset for each row, so it has to be set inside the row loop
        var sum = 0
        //find the combat elements in the current row and sum it 
        $(this).find('.combat').each(function () {
            var combat = $(this).text();
            if (!isNaN(combat) && combat.length !== 0) {
                sum += parseFloat(combat);
            }
        });
        //set the value of currents rows sum to the total-combat element in the current row
        $('.total-combat', this).html(sum);
    });
});