return $this->a / $this->b; break; default: return "Please Select One Operation..."; } } function getresult($a, $b, $c) { $this->a = $a; $this->b = $b; return $this->checkoperation($c); } } $calculator = new calculator(); if (isset($_POST['submit'])) { $answer = $calculator->getresult($_POST['number1'], $_POST['number2'], $_POST['operator']); } ?> <form method="post"> <table align="center"> <tr> <td><strong>Result :<?php echo $answer; ?> <strong></td> </tr> <tr> <td>Enter 1st Number</td> <td><input type="number" name="number1" required="true"></td> </tr>