Calcula IMC

<!DOCTYPE html>
<html>
<head>
    <title></title>
</head>
<body>
<h1>Calculo IMC</h1>
<input type="text" value="peso" size="20" id="Ps">Peso
<input type="text" value="altura" size="20" id="Al">Altura</br>
<button onclick="Calcula()">Calcula</button>
<div id="resultado"></div>

<script>
    function Calcula(){
    var x = document.getElementById('Ps').value;
    var y = document.getElementById('Al').value;
    var r = x / (y ** 2);
    document.getElementById('resultado').innerHTML=r;
};
</script>
</body>
</html>