Untitled

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Calculator</title>
</head>

<body>
    <form>
        <input type="text" id="monitor">
    </form>
    <button onclick="seven()">7</button>
    <button onclick="eight()">8</button>
    <button onclick="nine()">9</button>
    <br>
    <button onclick="four()">4</button>
    <button onclick="five()">5</button>
    <button onclick="six()">6</button>
    <br>
    <button onclick="one()">1</button>
    <button onclick="two()">2</button>
    <button onclick="three()">3</button>
    <br>
    <input type="button" value="-" onclick="dis('-')"/>
    <button onclick="zero()">0</button>
    <input type="button" value="+" onclick="dis('+')"/>

    <br>
    <input type="button" value="/" onclick="dis('/')"/>
    <input type="button" value="*" onclick="dis('*')"/>
    <input type="button" value="=" onclick="solve()"/>


</body>

<script src="main.js">
</script>

</html>