<!DOCTYPE html>
<html>
<body>
<p>Click the button to call myMethod() that display a number's half value.</p>
<button onclick="myFunction()">Try it</button>
<p id="demo"></p>
<script>
Number.prototype.myMethod = function() {
return this.valueOf() / 2;
};
function myFunction() {
var n = 55;
document.getElementById("demo").innerHTML = n.myMethod();
}
</script>
</body>
</html>