<html dir="rtl">
<head>
<style>.main{margin:10 auto;padding:25px;} .btn{border:1px solid #787878;margin:5px;padding:10px;}</style>
</head>
<body>
<div class="main">
<form action="#" method="post">
<label>n1: </label>
<input class="btn" type="text" name="num1" value="" >
<label>n2:</label>
<input class="btn" type="text" name="num2" value=""><br>
<input class="btn" type="submit" value="go" ><br>
<textarea rows="10" cols="50">
<?php
if(isset($_POST['num1']) || isset($_POST['num2'])){
echo $_POST['num1'];
echo $_POST['num2'];
}
?>
</textarea>
</form>
</div>
</body>
</html>