<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<?php
$number = $_GET['number'];
$func = $number+1;
echo "<form method='get' action =''>";
echo "<input type='text' name='number' value='$func'>";
echo "<input type='submit' value='Posten'>";
echo "</form>";
?>
</body>
</html>
Made by Thijs Aarnoudse