<?php
 
$str = "ba436090e93d81f8c2a3ef7b12526836";
 
$p = array(
    0 => "0",
    1 => "1",
    2 => "2abc",
    3 => "3def",
    4 => "4ghi",
    5 => "5jkl",
    6 => "6mno",
    7 => "7pqrs",
    8 => "8tuv",
    9 => "9wxyz"
);
 
$sum = 0;
 
for ($i = 0; $i < strlen($str); $i++) {
    foreach ($p as $number => $string) {
        $n = strpos($string, $str[$i]);
        if ($n > -1) {
            $sum += ($n + 1) * $number;
        }
    }
}
 
echo $sum;
 
?>