Please Cleanup if statements?

I am just wondering what the best way to cleanup this code is to make it smaller. Right now its an awful lot of code for what is being done.

if($num6 == 1){$num6 = "a";}
if($num6 == 2){$num6 = "b";}
if($num6 == 3){$num6 = "c";}
if($num6 == 4){$num6 = "d";}
if($num6 == 5){$num6 = "e";}
if($num6 == 6){$num6 = "f";}
if($num6 == 7){$num6 = "g";}
if($num6 == 8){$num6 = "h";}
if($num6 == 9){$num6 = "i";}
if($num6 == 10){$num6 = "j";}
if($num6 == 11){$num6 = "k";}
if($num6 == 12){$num6 = "l";}
if($num6 == 13){$num6 = "m";}
if($num6 == 14){$num6 = "n";}
if($num6 == 15){$num6 = "o";}
if($num6 == 16){$num6 = "p";}
if($num6 == 17){$num6 = "q";}
if($num6 == 18){$num6 = "r";}
if($num6 == 19){$num6 = "s";}
if($num6 == 20){$num6 = "t";}
if($num6 == 21){$num6 = "u";}
if($num6 == 22){$num6 = "v";}
if($num6 == 23){$num6 = "w";}
if($num6 == 24){$num6 = "x";}
if($num6 == 25){$num6 = "y";}
if($num6 == 26){$num6 = "z";}

Code (markup):

 

$a2z = range('a', 'z');

$num6 = $a2z[$num6];

PHP:

 

Thank you for the response. As I was waiting it hit me to just use the code below:

$letters = 'abcdefghijklmnopqrstuvwxyz';
$num6 = "$letters[$num6]";

 

This will work too:

$num6=chr($num6+96);

PHP: