Script php to know how many possible combinations you can have [closed]

I would like to create a simple script, just to know the number of possible combinations.

You would not see the list of combinations, but only how many digits you can have, and the numbers and or letters can be reordered. Ex :

$Valores = "1, 2"; 
$Digito  = 2; //Quantidade de dígitos.

echo $Resultado = 6; //Possíveis combinações 1,2,12,21,22,11