<div class="numbers">
<form method='post'><input type="submit" name='num' value='1'></form>
<form method='post'><input type="submit" name='num' value='2'></form>
<form method='post'><input type="submit" name='num' value='3'></form>
<form method='post'><input type="submit" name='num' value='4'></form>
<form method='post'><input type="submit" name='num' value='5'></form>
<form method='post'><input type="submit" name='num' value='6'></form>
<form method='post'><input type="submit" name='num' value='7'></form>
<form method='post'><input type="submit" name='num' value='8'></form>
<form method='post'><input type="submit" name='num' value='9'></form>
<form method='post'><input type="submit" name='num' value='0'></form>
<form method='post'><input type="submit" name='null' value='d' style='visibility: hidden;'></form>
<form method='post'><input type="submit" name='=' value='='></form>
</div>
<div class="operators">
<form method='post'><input type="submit" name='operator' value='+'></form>
<form method='post'><input type="submit" name='operator' value='-'></form>
<form method='post'><input type="submit" name='operator' value='/'></form>
<form method='post'><input type="submit" name='operator' value='x'></form>
</div>
<?php
if (isset($_POST['='])) {
$sum = new Sum(12, 3);
echo "<script>\$('.display span').append('" . $sum->makeSum(12, 3) . "');</script>";
}
?>
</div>
</div>
</body>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.4/jquery.min.js"></script>
</html>
