in.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <p>
        first number <input id ="numberOne">
    </p>
    <p>second number <input id ="numberTwo"></p>
    <button onclick="add()">
        add
    </button>
    <button onclick="sub()">
        subtract
    </button>
    <button onclick="mul()">
        divide
    </button>
    <button onclick="divi()">
        Multiply
    </button>
<p>final answer <span id = "answer"></span></p>
<p>final answer(subtraction) <span id = "answersub"></span></p>
<p>final answer(multiplication) <span id = "answermul"></span></p>
<p>final answer(divide) <span id = "answerdivi"></span></p>
</body>

<script src="./script.js"></script>
</html>