Using numbersapi.com with JSONP

HTML

<span id="number-fact"></span>

<script>
    function showNumber(str) {
        document.getElementById('number-fact').innerText = str;
    }

    (function() {
        var scriptTag = document.createElement('script');
        scriptTag.async = true;
        scriptTag.src = "http://numbersapi.com/555/math?callback=showNumber";
        document.body.appendChild(scriptTag);
    })();
</script>