do so you can type
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Enhanced Calculator</title>
    <style>
        body {
            font-family: 'Arial', sans-serif;
            background-color: #f5f5f5;
            display: flex;
            align-items: center;
            justify-content: center;
            height: 100vh;
            margin: 0;
        }

        .calculator {
            background-color: #fff;
            border: 1px solid #ccc;
            border-radius: 5px;
            box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
            padding: 20px;
            text-align: center;
        }

        .result {
            width: 100%;
            height: 40px;
            font-size: 24px;
            margin-bottom: 10px;
            text-align: right;
            padding: 5px;
            border: 1px solid #ccc;
            border-radius: 3px;
        }

        .btn-container {
            display: grid;
            grid-template-columns: repeat(4, 1fr);
            grid-gap: 10px;
            margin-bottom: 10px;
        }

        .btn {
            width: 100%;
            height: 50px;
            font-size: 18px;
            cursor: pointer;
            background-color: #4caf50;
            border: 1px solid #4caf50;
            border-radius: 3px;
            color: #fff;
            transition: background-color 0.3s ease;
        }

        .btn.operator {
            background-color: #ff9800;
            border: 1px solid #ff9800;
        }

        .btn.special {
            background-color: #2196f3;
            border: 1px solid #2196f3;
        }

        .btn.double {
            grid-column: span 2;
        }

        .btn.double-zero {
            grid-column: span 2;
        }

        .btn:hover {
            background-color: #45a049;
        }
    </style>
</head>
<body>
    <div class="calculator">
        <input class="result" type="text" name="result" readonly>
        <div class="btn-container">
            <input class="btn" type="button" value="7" onclick="addToResult('7')">
            <input class="btn" type="button" value="8" onclick="addToResult('8')">
            <input class="btn" type="button" value="9" onclick="addToResult('9')">
            <input class="btn operator" type="button" value="/" onclick="addToResult('/')">

            <input class="btn" type="button" value="4" onclick="addToResult('4')">
            <input class="btn" type="button" value="5" onclick="addToResult('5')">
            <input class="btn" type="button" value="6" onclick="addToResult('6')">
            <input class="btn operator" type="button" value="*" onclick="addToResult('*')">

            <input class="btn" type="button" value="1" onclick="addToResult('1')">
            <input class="btn" type="button" value="2" onclick="addToResult('2')">
            <input class="btn" type="button" value="3" onclick="addToResult('3')">
            <input class="btn operator" type="button" value="-" onclick="addToResult('-')">

            <input class="btn double" type="button" value="0" onclick="addToResult('0')">
            <input class="btn" type="button" value="." onclick="addToResult('.')">
            <input class="btn operator" type="button" value="+" onclick="addToResult('+')">
            <input class="btn operator" type="button" value="=" onclick="calculate()">

            <input class="btn double" type="button" value="C" onclick="clearResult()">
        </div>
    </div>
    <script>
        function addToResult(value) {
            document.querySelector('.result').value += value;
        }

        function calculate() {
            let result = eval(document.querySelector('.result').value);
            document.querySelector('.result').value = result;
        }

        function clearResult() {
            document.querySelector('.result').value = '';
        }
    </script>
</body>
</html>