Escrever no HTML com innerHTML

<html>
<body>

<h1>My First Web Page</h1>
<p>My First Paragraph</p>

<p id="demonstracao"></p>

<script>

// Changing the innerHTML property of an HTML element is a common way to display data in HTML.
document.getElementById("demonstracao").innerHTML = 4 + 3;
</script>

</body>
</html>