html elements can't have multiple ids

[bobbysebolao]

Ids should also be unique, meaning that an id can only be used once on a single element.

            <div class="row">
                <button type="button" id="seven numbers">7</button>
                <button type="button" id="eight numbers">8</button>
                <button type="button" id="none numbers">9</button>
                <button type="button" id="multiply operators">x</button>
            </div>

HTML elements can have multiple class names, so to fix the issue here we could set class='numbers' on each of the buttons