<?php if(isset($_POST['submit'])) { $num1=$_POST['number1']; $num2=$_POST['number2']; function hcf($i1,$i2) { if($i2!=0) { return hcf($i2,$i1%$i2); } else { return $i1; } } $hcfofnumber=hcf($num1,$num2); } ?>