Program to find prime numbers in between a range

<?php
//error_reporting(E_ALL);
//Program to find prime numbers in between a range

$num =23;

for( $j = 2; $j <= $num; $j++ )
{
for( $k = 2; $k < $j; $k++ )
{
if( $j % $k == 0 )
{
break;
}

}
if( $k == $j )
echo "Prime Number : ", $j, "<br>";
}
?>