calculadora.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=device-width, initial-scale=1.0">
    <title>Calculadora Simples</title>
    <link rel="stylesheet" href="calculadora.css">
</head>
<body>
    <body>
        <h1>Calculadora</h1>
    <div class="calculator">
      <div class="display">
        <input type="text" readonly>
      </div>
      <div class="keys">
        <button>7</button>
        <button>8</button>
        <button>9</button>
        <button>/</button>
        <button>4</button>
        <button>5</button>
        <button>6</button>
        <button>*</button>
        <button>1</button>
        <button>2</button>
        <button>3</button>
        <button>-</button>
        <button>0</button>
        <button>.</button>
        <button>=</button>
        <button>+</button>
      </div>
    </div>
</body>
<script src="calculadora.js"></script>
</html>