php five

<?php

if (isset ($_POST ['b1'])){

function add() {
$a = $_POST ['num1'];
$b = $_POST ['num2'];
echo  $a + $b ;
}
?>
   <h3>  <?php add () ?> </h3>
   <?php
}
?>

<?php

if (isset ($_POST ['b2'])){

function add() {
$a = $_POST ['num1'];
$b = $_POST ['num2'];
echo  $a - $b ;
}
?>
   <h3>  <?php add () ?> </h3>
   <?php
}
?>

<?php

if (isset ($_POST ['b3'])){

function add() {
$a = $_POST ['num1'];
$b = $_POST ['num2'];
echo  $a * $b ;
}
?>
   <h3>  <?php add () ?> </h3>
   <?php
}
?>

<?php

if (isset ($_POST ['b4'])){

function add() {
$a = $_POST ['num1'];
$b = $_POST ['num2'];
echo  $a / $b ;
}
?>
   <h3>  <?php add () ?> </h3>
   <?php
}
?>


<form method="post">
<label> Enter first number </label>
<input type="number" name="num1"/> 

</br>
 </br>
     
     
<label> Enter second number </label>
<input type="number" name="num2"/>     
        </br>
        </br>
        <input type="submit" value="Add" name="b1"/>
     
        <input type="submit" value="Sub" name="b2"/>
     
        <input type="submit" value="Mulip" name="b3"/>
     
        <input type="submit" value="Divid" name="b4"/>
   
</form>