<html>
	<head>
	<style>
		table, td, th {
			border: 1px solid black; 
			width: 35%;
			text-align: center; 
			background-color: lightgray;
		}
		table { margin: auto; } 
		input,p { text-align:right; }
	</style>
</head>

<body>
	<form method="post" action="prog8a.php">
		<table>
		<caption><h2> SIMPLE CALCULATOR </h2></caption>
		<tr>
			<td>First Number:</td><td><input type="text" name="num1" /></td>
			<td rowspan="2"><button type="submit" name="submit" value="calculate">Calculate</td></tr>
		<tr>
			<td>Second Number:</td><td><input type="text" name="num2"/></td>
		</tr>
	</form>
	
	<?php
	if(isset($_POST['submit'])) // it checks if the input submit is filled
	{
		$num1 = $_POST['num1'];
		$num2 = $_POST['num2']; 
		if(is_numeric($num1) and is_numeric($num2) )
		{
			echo "<tr><td> Addition :</td><td><p>".($num1+$num2)."</p></td>"; 
			echo "<tr><td> Subtraction :</td><td><p> ".($num1-$num2)."</p></td>"; 
			echo "<tr><td> Multiplication :</td><td><p>".($num1*$num2)."</p></td>"; 
			echo "<tr><td>Division :</td><td><p> ".($num1/$num2)."</p></td>";
			echo "</table>";
		}
		else
		{
			echo"<script> alert(' ENTER VALID NUMBER');</script>";
		}
	}
	?>
</body>
</html>