index.html

<!doctype html>
<html lang="ru">
<head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
    <script src="number_plugin/number_plugin.min.js" type="text/javascript"></script>
    <link href="number_plugin/number_plugin.css" type="text/css" rel="stylesheet">
    <link rel="stylesheet" href="style.css" type="text/css">
    <script src="app.js" type="text/javascript"></script>
</head>
<body>
<div class="wrapper">
    <div>
        <input type="number" class="numb" id="1" value="1">
        <input type="number" class="numb" id="2" value="1">
    </div>
</div>
</body>
</html>