[Nexus]

<table>
    <tr class="tab">
        <td class="one">3</td>
        <td class="one">4</td>
        <td class="tab1">info</td>
        <td class="tab2">9</td>
    </tr>
    <tr>
    <tr class="tab">
        <td class="one">3</td>
        <td class="one">4</td>
        <td class="tab1">info</td>
        <td class="tab2">9</td>
    </tr>
    <tr>
    <tr class="tab">
        <td class="one">3</td>
        <td class="one">4</td>
        <td class="tab1">info</td>
        <td class="tab2">9</td>
    </tr>
</table>
<script>
document.querySelectorAll('td.one').forEach(el => {
    el.insertAdjacentHTML('afterend', '<td class="number">' + el.textContent + '</td>');
});
</script>