<!DOCTYPE html>
<html>
<head>
<title>Calculator</title>
</head>
<body>

<h2>Calculator</h2>

Number 1: <input type="number" id="n1"><br><br>
Number 2: <input type="number" id="n2"><br><br>

<button onclick="add()">add</button>
<button onclick="sub()">Sub</button>
<button onclick="mul()">Mul</button>
<button onclick="div()">Div</button>

<h3 id="result"></h3>

<script>
function add(){
  let a = document.getElementById("n1").value;
  let b = document.getElementById("n2").value;
  document.getElementById("result").innerHTML = a+b;
}

function sub(){
  let a = document.getElementById("n1").value;
  let b = document.getElementById("n2").value;
  document.getElementById("result").innerHTML = a-b;
}

function mul(){
  let a = document.getElementById("n1").value;
  let b = document.getElementById("n2").value;
  document.getElementById("result").innerHTML = a*b;
}

function div(){
  let a = document.getElementById("n1").value;
  let b = document.getElementById("n2").value;
  document.getElementById("result").innerHTML = a/b;
}
</script>

</body>
</html>
